diff --git a/src/include/int.hpp b/src/include/int.hpp
new file mode 100644
index 0000000..32ca7e3
--- /dev/null
+++ b/src/include/int.hpp
@@ -0,0 +1,425 @@
+#include <gmp.h>
+#include <gmpxx.h>
+#include <string>
+
+/**
+ * @brief Options for `base` parameter used in GMP's `mpz_set_str` and
+ * `mpz_sizeinbase`.
+ * @see https://gmplib.org/manual/Assigning-Integers
+ *
+ * `base_N`: no characters, no case sensitivity.
+ * `ci_N`: case-insensitive (`A`=`10`, `a`=`10`)
+ * `cs_N`: case-sensitive (`A`=`10`, `a`=`36`)
+ */
+enum class base {
+  base_2 = 2,
+  base_3 = 3,
+  base_4 = 4,
+  base_5 = 5,
+  base_6 = 6,
+  base_7 = 7,
+  base_8 = 8,
+  base_9 = 9,
+  ci_10 = 10,
+  ci_11 = 11,
+  ci_12 = 12,
+  ci_13 = 13,
+  ci_14 = 14,
+  ci_15 = 15,
+  ci_16 = 16,
+  ci_17 = 17,
+  ci_18 = 18,
+  ci_19 = 19,
+  ci_20 = 20,
+  ci_21 = 21,
+  ci_22 = 22,
+  ci_23 = 23,
+  ci_24 = 24,
+  ci_25 = 25,
+  ci_26 = 26,
+  ci_27 = 27,
+  ci_28 = 28,
+  ci_29 = 29,
+  ci_30 = 30,
+  ci_31 = 31,
+  ci_32 = 32,
+  ci_33 = 33,
+  ci_34 = 34,
+  ci_35 = 35,
+  ci_36 = 36,
+  cs_37 = 37,
+  cs_38 = 38,
+  cs_39 = 39,
+  cs_40 = 40,
+  cs_41 = 41,
+  cs_42 = 42,
+  cs_43 = 43,
+  cs_44 = 44,
+  cs_45 = 45,
+  cs_46 = 46,
+  cs_47 = 47,
+  cs_48 = 48,
+  cs_49 = 49,
+  cs_50 = 50,
+  cs_51 = 51,
+  cs_52 = 52,
+  cs_53 = 53,
+  cs_54 = 54,
+  cs_55 = 55,
+  cs_56 = 56,
+  cs_57 = 57,
+  cs_58 = 58,
+  cs_59 = 59,
+  cs_60 = 60,
+  cs_61 = 61,
+  cs_62 = 62,
+  binary = base_2,
+  octal = base_8,
+  decimal = ci_10,
+  hexadecimal = ci_16,
+};
+
+/**
+ * @brief Options for `base` parameter used in GMP's `mpz_get_str`.
+ * @see https://gmplib.org/manual/Converting-Integers
+ *
+ * `base_N`: case sensitive. It doesn't have its upper and lower case versions.
+ *
+ * `lc_N`: lower-case, base N. All letters are lower case.
+ *
+ * `uc_N`: upper-case, base N. All letters are upper case.
+ */
+enum class print_base {
+  lc_2 = 2,
+  lc_3 = 3,
+  lc_4 = 4,
+  lc_5 = 5,
+  lc_6 = 6,
+  lc_7 = 7,
+  lc_8 = 8,
+  lc_9 = 9,
+  lc_10 = 10,
+  lc_11 = 11,
+  lc_12 = 12,
+  lc_13 = 13,
+  lc_14 = 14,
+  lc_15 = 15,
+  lc_16 = 16,
+  lc_17 = 17,
+  lc_18 = 18,
+  lc_19 = 19,
+  lc_20 = 20,
+  lc_21 = 21,
+  lc_22 = 22,
+  lc_23 = 23,
+  lc_24 = 24,
+  lc_25 = 25,
+  lc_26 = 26,
+  lc_27 = 27,
+  lc_28 = 28,
+  lc_29 = 29,
+  lc_30 = 30,
+  lc_31 = 31,
+  lc_32 = 32,
+  lc_33 = 33,
+  lc_34 = 34,
+  lc_35 = 35,
+  lc_36 = 36,
+  uc_2 = -2,
+  uc_3 = -3,
+  uc_4 = -4,
+  uc_5 = -5,
+  uc_6 = -6,
+  uc_7 = -7,
+  uc_8 = -8,
+  uc_9 = -9,
+  uc_10 = -10,
+  uc_11 = -11,
+  uc_12 = -12,
+  uc_13 = -13,
+  uc_14 = -14,
+  uc_15 = -15,
+  uc_16 = -16,
+  uc_17 = -17,
+  uc_18 = -18,
+  uc_19 = -19,
+  uc_20 = -20,
+  uc_21 = -21,
+  uc_22 = -22,
+  uc_23 = -23,
+  uc_24 = -24,
+  uc_25 = -25,
+  uc_26 = -26,
+  uc_27 = -27,
+  uc_28 = -28,
+  uc_29 = -29,
+  uc_30 = -30,
+  uc_31 = -31,
+  uc_32 = -32,
+  uc_33 = -33,
+  uc_34 = -34,
+  uc_35 = -35,
+  uc_36 = -36,
+  base_37 = 37,
+  base_38 = 38,
+  base_39 = 39,
+  base_40 = 40,
+  base_41 = 41,
+  base_42 = 42,
+  base_43 = 43,
+  base_44 = 44,
+  base_45 = 45,
+  base_46 = 46,
+  base_47 = 47,
+  base_48 = 48,
+  base_49 = 49,
+  base_50 = 50,
+  base_51 = 51,
+  base_52 = 52,
+  base_53 = 53,
+  base_54 = 54,
+  base_55 = 55,
+  base_56 = 56,
+  base_57 = 57,
+  base_58 = 58,
+  base_59 = 59,
+  base_60 = 60,
+  base_61 = 61,
+  base_62 = 62,
+  octal_lower_case = lc_8,
+  hex_lower_case = lc_16,
+  decimal = lc_10,
+  binary = lc_2,
+  octal_upper_case = uc_8,
+  hex_upper_case = uc_16,
+};
+
+base print_base_to_base(print_base);
+
+/**
+ * @brief  is an high-performance, arbitrary precision Integer class for mash
+ */
+class Int {
+private:
+  mpz_t inner;
+
+public:
+  Int();
+  Int(const Int &);
+  Int(unsigned long);
+  Int(long);
+  Int(double);
+  Int(const std::string &, base);
+
+  unsigned long to_ul();
+  long to_l();
+  double to_d();
+  std::string to_string(print_base);
+
+  void swap(Int &);
+  void operator+(const Int &);
+  void operator+(unsigned long);
+  void operator+(long);
+
+  void operator-(const Int &);
+  void operator-(unsigned long);
+  void operator-(long);
+
+  void operator*(const Int &);
+  void operator*(unsigned long);
+  void operator*(long);
+
+  void operator/(const Int &);
+  void operator/(unsigned long);
+  void operator/(long);
+
+  void operator%(const Int &);
+  void operator%(unsigned long);
+
+  void add_mul(Int &);
+  void add_mul(unsigned long);
+  void add_mul(long);
+
+  void sub_mul(Int &);
+  void sub_mul(unsigned long);
+  void sub_mul(long);
+
+  void mul_2exp(unsigned long);
+
+  void operator~();
+
+  void abs();
+
+  void ceil_div_quotient(Int &);
+  void ceil_div_remainder(Int &);
+  void ceil_div_both(Int &);
+  void ceil_div(unsigned long);
+  void ceil_div_both(unsigned long);
+  void ceil_div_quotient(unsigned long);
+  void ceil_div_remainder(unsigned long);
+  void ceil_div(long);
+  void ceil_div_both(long);
+  void ceil_div_quotient(long);
+  void ceil_div_remainder(long);
+  void ceil_div_quotient_2exp(unsigned long);
+  void ceil_div_remainder_2exp(unsigned long);
+
+  void floor_div_quotient(Int &);
+  void floor_div_remainder(Int &);
+  void floor_div_both(Int &);
+  void floor_div(unsigned long);
+  void floor_div_both(unsigned long);
+  void floor_div_quotient(unsigned long);
+  void floor_div_remainder(unsigned long);
+  void floor_div(long);
+  void floor_div_both(long);
+  void floor_div_quotient(long);
+  void floor_div_remainder(long);
+  void floor_div_quotient_2exp(unsigned long);
+  void floor_div_remainder_2exp(unsigned long);
+
+  void truncate_div_quotient(Int &);
+  void truncate_div_remainder(Int &);
+  void truncate_div_both(Int &);
+  void truncate_div(unsigned long);
+  void truncate_div_both(unsigned long);
+  void truncate_div_quotient(unsigned long);
+  void truncate_div_remainder(unsigned long);
+  void truncate_div(long);
+  void truncate_div_both(long);
+  void truncate_div_quotient(long);
+  void truncate_div_remainder(long);
+  void truncate_div_quotient_2exp(unsigned long);
+  void truncate_div_remainder_2exp(unsigned long);
+
+  void mod(Int &);
+  void mod(unsigned long);
+  void mod(long);
+
+  void div_exact(Int &);
+  void div_exact(unsigned long);
+  void div_exact(long);
+
+  int divisible(Int &);
+  int divisible(unsigned long);
+  int divisible(long);
+  int divisible_2exp(unsigned long);
+
+  int congruent(Int &);
+  int congruent(unsigned long);
+  int congruent(long);
+  int congruent_2exp(unsigned long);
+
+  void mod_pow(Int &);
+  void mod_pow(unsigned long);
+  void mod_pow(long);
+
+  void powm_sec(Int &);
+
+  void pow(Int &);
+  void pow(unsigned long, unsigned long);
+  void pow(long, unsigned long);
+
+  ~Int() { mpz_clear(inner); };
+};
+
+/*
+///
+/// Enum for the number's sign.
+///
+/// `Zero` is for when number is zero.
+///
+pub const Sign = enum(i8) {
+    Negative = -1,
+    Positive = 1,
+    Zero = 0,
+
+    pub fn toChar(self: @This()) u8 {
+        return switch (self) {
+            .Negative => '-',
+            .Positive => '+',
+            .Zero => '0',
+        };
+    }
+
+    pub fn toString(self: @This()) []const u8 {
+        return switch (self) {
+            .Negative => "negative",
+            .Positive => "positive",
+            .Zero => "zero",
+        };
+    }
+};
+
+///
+/// Enum for the comparison of two numbers.
+///
+pub const Ordering = enum(i8) {
+    Less = -1,
+    Greater = 1,
+    Equals = 0,
+
+    const Self = @This();
+
+    pub fn toChar(self: Self) u8 {
+        return switch (self) {
+            .Less => '<',
+            .Greater => '>',
+            .Equals => '=',
+        };
+    }
+
+    pub fn toString(self: Self) []const u8 {
+        return switch (self) {
+            .Less => "less",
+            .Greater => "greater",
+            .Equals => "equals",
+        };
+    }
+
+    pub fn fromC(num: c_int) Self {
+        if (num < 0) return .Less;
+        if (num > 0) return .Greater;
+        return .Equals;
+    }
+};
+
+/// Enum for the number's parity.
+pub const Parity = enum(i8) {
+    Even = 0,
+    Odd = 1,
+
+    pub fn toString(self: @This()) []const u8 {
+        return switch (self) {
+            .Even => "even",
+            .Odd => "odd",
+        };
+    }
+};
+
+////
+/// Rounding methods for division.
+///
+/// `Truncate` rounds the integer towards 0.
+/// `Ceil` rounds the integer towards positive infinity.
+/// `Floor` rounds the integer towrds positiv infinity.
+///
+/// |`Number`|`Truncate`|`Ceil`|`Floor`|
+/// |--------|----------|------|-------|
+/// |`4.5`   |`4`       |`5`   |`4`    |
+/// |`-4.5`  |`-4`      |`-4`  |`-5`   |
+///
+pub const RoundingMethod = enum(i8) {
+    Truncate = 0,
+    Ceil = 1,
+    Floor = -1,
+};
+
+///
+/// Option for which result will be written to the integer.
+///
+pub const Output = enum(i8) {
+    Quotient = 0,
+    Remainder = 1,
+};
+*/
\ No newline at end of file
diff --git a/src/int.cpp b/src/int.cpp
new file mode 100644
index 0000000..ea2b9d4
--- /dev/null
+++ b/src/int.cpp
@@ -0,0 +1,342 @@
+#include <cmath>
+#include <cstdlib>
+#include <gmp.h>
+#include <int.hpp>
+#include <string>
+#include <utility>
+
+Int::Int() { mpz_init(this->inner); };
+Int::Int(const Int &big) { mpz_init_set(this->inner, big.inner); };
+Int::Int(unsigned long ul) { mpz_init_set_ui(this->inner, ul); };
+Int::Int(long l) { mpz_init_set_si(this->inner, l); };
+Int::Int(double d) { mpz_init_set_d(this->inner, d); };
+Int::Int(const std::string &str, base b) {
+  int result = mpz_init_set_str(this->inner, str.data(), static_cast<int>(b));
+  if (result == 1)
+    throw std::exception();
+};
+
+base print_base_to_base(print_base p_base) {
+  switch (p_base) {
+  case print_base::lc_2:
+  case print_base::uc_2:
+    return base::base_2;
+  case print_base::lc_3:
+  case print_base::uc_3:
+    return base::base_3;
+  case print_base::lc_4:
+  case print_base::uc_4:
+    return base::base_4;
+  case print_base::lc_5:
+  case print_base::uc_5:
+    return base::base_5;
+  case print_base::lc_6:
+  case print_base::uc_6:
+    return base::base_6;
+  case print_base::lc_7:
+  case print_base::uc_7:
+    return base::base_7;
+  case print_base::lc_8:
+  case print_base::uc_8:
+    return base::base_8;
+  case print_base::lc_9:
+  case print_base::uc_9:
+    return base::base_9;
+  case print_base::lc_10:
+  case print_base::uc_10:
+    return base::ci_10;
+  case print_base::lc_11:
+  case print_base::uc_11:
+    return base::ci_11;
+  case print_base::lc_12:
+  case print_base::uc_12:
+    return base::ci_12;
+  case print_base::lc_13:
+  case print_base::uc_13:
+    return base::ci_13;
+  case print_base::lc_14:
+  case print_base::uc_14:
+    return base::ci_14;
+  case print_base::lc_15:
+  case print_base::uc_15:
+    return base::ci_15;
+  case print_base::lc_16:
+  case print_base::uc_16:
+    return base::ci_16;
+  case print_base::lc_17:
+  case print_base::uc_17:
+    return base::ci_17;
+  case print_base::lc_18:
+  case print_base::uc_18:
+    return base::ci_18;
+  case print_base::lc_19:
+  case print_base::uc_19:
+    return base::ci_19;
+  case print_base::lc_20:
+  case print_base::uc_20:
+    return base::ci_20;
+  case print_base::lc_21:
+  case print_base::uc_21:
+    return base::ci_21;
+  case print_base::lc_22:
+  case print_base::uc_22:
+    return base::ci_22;
+  case print_base::lc_23:
+  case print_base::uc_23:
+    return base::ci_23;
+  case print_base::lc_24:
+  case print_base::uc_24:
+    return base::ci_24;
+  case print_base::lc_25:
+  case print_base::uc_25:
+    return base::ci_25;
+  case print_base::lc_26:
+  case print_base::uc_26:
+    return base::ci_26;
+  case print_base::lc_27:
+  case print_base::uc_27:
+    return base::ci_27;
+  case print_base::lc_28:
+  case print_base::uc_28:
+    return base::ci_28;
+  case print_base::lc_29:
+  case print_base::uc_29:
+    return base::ci_29;
+  case print_base::lc_30:
+  case print_base::uc_30:
+    return base::ci_30;
+  case print_base::lc_31:
+  case print_base::uc_31:
+    return base::ci_31;
+  case print_base::lc_32:
+  case print_base::uc_32:
+    return base::ci_32;
+  case print_base::lc_33:
+  case print_base::uc_33:
+    return base::ci_33;
+  case print_base::lc_34:
+  case print_base::uc_34:
+    return base::ci_34;
+  case print_base::lc_35:
+  case print_base::uc_35:
+    return base::ci_35;
+  case print_base::lc_36:
+  case print_base::uc_36:
+    return base::ci_36;
+  case print_base::base_37:
+    return base::cs_37;
+  case print_base::base_38:
+    return base::cs_38;
+  case print_base::base_39:
+    return base::cs_39;
+  case print_base::base_40:
+    return base::cs_40;
+  case print_base::base_41:
+    return base::cs_41;
+  case print_base::base_42:
+    return base::cs_42;
+  case print_base::base_43:
+    return base::cs_43;
+  case print_base::base_44:
+    return base::cs_44;
+  case print_base::base_45:
+    return base::cs_45;
+  case print_base::base_46:
+    return base::cs_46;
+  case print_base::base_47:
+    return base::cs_47;
+  case print_base::base_48:
+    return base::cs_48;
+  case print_base::base_49:
+    return base::cs_49;
+  case print_base::base_50:
+    return base::cs_50;
+  case print_base::base_51:
+    return base::cs_51;
+  case print_base::base_52:
+    return base::cs_52;
+  case print_base::base_53:
+    return base::cs_53;
+  case print_base::base_54:
+    return base::cs_54;
+  case print_base::base_55:
+    return base::cs_55;
+  case print_base::base_56:
+    return base::cs_56;
+  case print_base::base_57:
+    return base::cs_57;
+  case print_base::base_58:
+    return base::cs_58;
+  case print_base::base_59:
+    return base::cs_59;
+  case print_base::base_60:
+    return base::cs_60;
+  case print_base::base_61:
+    return base::cs_61;
+  case print_base::base_62:
+    return base::cs_62;
+  }
+
+  std::unreachable();
+}
+
+unsigned long Int::to_ul() { return mpz_get_ui(this->inner); };
+long Int::to_l() { return mpz_get_si(this->inner); };
+double Int::to_d() { return mpz_get_d(this->inner); };
+std::string Int::to_string(print_base base) {
+  int print_base_int = static_cast<int>(base);
+
+  char *str = mpz_get_str(NULL, print_base_int, this->inner);
+
+  std::string res(str);
+
+  free(str);
+
+  return res;
+};
+
+void Int::swap(Int &rhs) { mpz_swap(this->inner, rhs.inner); }
+
+void Int::operator+(const Int &rhs) {
+  mpz_add(this->inner, this->inner, rhs.inner);
+};
+
+void Int::operator+(unsigned long rhs) {
+  mpz_add_ui(this->inner, this->inner, rhs);
+};
+
+void Int::operator+(long rhs) {
+  if (rhs < 0)
+    mpz_sub_ui(this->inner, this->inner, std::abs(rhs));
+  else
+    mpz_add_ui(this->inner, this->inner, rhs);
+};
+
+void Int::operator-(const Int &rhs) {
+  mpz_sub(this->inner, this->inner, rhs.inner);
+};
+
+void Int::operator-(unsigned long rhs) {
+  mpz_sub_ui(this->inner, this->inner, rhs);
+};
+
+void Int::operator-(long rhs) {
+  if (rhs < 0)
+    mpz_add_ui(this->inner, this->inner, std::abs(rhs));
+  else
+    mpz_sub_ui(this->inner, this->inner, rhs);
+};
+
+void Int::operator*(const Int &rhs) {
+  mpz_mul(this->inner, this->inner, rhs.inner);
+};
+
+void Int::operator*(unsigned long rhs) {
+  mpz_mul_ui(this->inner, this->inner, rhs);
+};
+
+void Int::operator*(long rhs) {
+  if (rhs < 0) {
+    mpz_mul_ui(this->inner, this->inner, std::abs(rhs));
+    this->operator~();
+  } else
+    mpz_mul_ui(this->inner, this->inner, rhs);
+};
+
+void Int::operator/(const Int &rhs) {
+  mpz_tdiv_q(this->inner, this->inner, rhs.inner);
+};
+
+void Int::operator/(unsigned long rhs) {
+  mpz_tdiv_q_ui(this->inner, this->inner, rhs);
+};
+
+void Int::operator/(long rhs) {
+  if (rhs < 0) {
+    mpz_tdiv_q_ui(this->inner, this->inner, std::abs(rhs));
+    this->operator~();
+  } else
+    mpz_tdiv_q_ui(this->inner, this->inner, rhs);
+};
+
+void Int::operator%(const Int &rhs) {
+  mpz_mod(this->inner, this->inner, rhs.inner);
+};
+
+void Int::operator%(unsigned long rhs) {
+  mpz_mod_ui(this->inner, this->inner, rhs);
+};
+
+void add_mul(Int &);
+void add_mul(unsigned long);
+void add_mul(long);
+
+void sub_mul(Int &);
+void sub_mul(unsigned long);
+void sub_mul(long);
+
+void mul_2exp(unsigned long);
+
+void Int::operator~() { mpz_neg(this->inner, this->inner); };
+
+void abs();
+
+void ceil_div_quotient(Int &);
+void ceil_div_remainder(Int &);
+void ceil_div_both(Int &);
+void ceil_div(unsigned long);
+void ceil_div_both(unsigned long);
+void ceil_div_quotient(unsigned long);
+void ceil_div_remainder(unsigned long);
+void ceil_div(long);
+void ceil_div_both(long);
+void ceil_div_quotient(long);
+void ceil_div_remainder(long);
+void ceil_div_quotient_2exp(unsigned long);
+void ceil_div_remainder_2exp(unsigned long);
+
+void floor_div_quotient(Int &);
+void floor_div_remainder(Int &);
+void floor_div_both(Int &);
+void floor_div(unsigned long);
+void floor_div_both(unsigned long);
+void floor_div_quotient(unsigned long);
+void floor_div_remainder(unsigned long);
+void floor_div(long);
+void floor_div_both(long);
+void floor_div_quotient(long);
+void floor_div_remainder(long);
+void floor_div_quotient_2exp(unsigned long);
+void floor_div_remainder_2exp(unsigned long);
+
+void truncate_div_quotient(Int &);
+void truncate_div_remainder(Int &);
+void truncate_div_both(Int &);
+void truncate_div(unsigned long);
+void truncate_div_both(unsigned long);
+void truncate_div_quotient(unsigned long);
+void truncate_div_remainder(unsigned long);
+void truncate_div(long);
+void truncate_div_both(long);
+void truncate_div_quotient(long);
+void truncate_div_remainder(long);
+void truncate_div_quotient_2exp(unsigned long);
+void truncate_div_remainder_2exp(unsigned long);
+
+void mod(Int &);
+void mod(unsigned long);
+void mod(long);
+
+void div_exact(Int &);
+void div_exact(unsigned long);
+void div_exact(long);
+
+int divisible(Int &);
+int divisible(unsigned long);
+int divisible(long);
+int divisible_2exp(unsigned long);
+
+int congruent(Int &);
+int congruent(unsigned long);
+int congruent(long);
+int congruent_2exp(unsigned long);