diff --git a/include/bmath.hh b/include/bmath.hh
index c58b0a5..6b787c1 100644
--- a/include/bmath.hh
+++ b/include/bmath.hh
@@ -1,8 +1,55 @@
 #ifndef BMATH_HEADER_ONLY_MATH_LIB
 #define BMATH_HEADER_ONLY_MATH_LIB
 
+#include <compare>
+#include <concepts>
+#include <optional>
+
 namespace bmath {
-inline int add(int x, int y) { return x + y; }
-} // namespace bmath
+
+template <std::integral IntegralType, typename Modulus = std::nullopt_t>
+  requires(std::integral<Modulus> || std::is_same_v<Modulus, std::nullopt_t>)
+class mint {
+ public:
+  [[nodiscard]] constexpr explicit mint() : value{} {}
+  [[nodiscard]] constexpr explicit mint(IntegralType _value) : value{_value} {}
+  [[nodiscard]] constexpr explicit operator IntegralType() const noexcept {
+    return value;
+  }
+
+  template <typename OtherIntegralType, typename OtherModulus>
+  [[nodiscard]] constexpr mint operator+(
+      mint<OtherIntegralType, OtherModulus> const& otherMint) const noexcept {
+    return mint{value + otherMint.value};
+  }
+
+  [[nodiscard]] constexpr mint& operator-(mint const& other) const noexcept {}
+  [[nodiscard]] constexpr mint& operator*(mint const& other) const noexcept {}
+  [[nodiscard]] constexpr mint& operator/(mint const& other) const noexcept {}
+  [[nodiscard]] constexpr mint& operator%(mint const& other) const noexcept {}
+
+  friend constexpr bool operator==(std::convertible_to<IntegralType> auto a,
+                                   mint const& b) noexcept {
+    return static_cast<IntegralType>(a) == b.value;
+  }
+
+  friend constexpr bool operator==(
+      mint const& a, std::convertible_to<IntegralType> auto b) noexcept {
+    return a.value == static_cast<IntegralType>(b);
+  }
+
+  template <typename OtherIntegralType, typename OtherModulus>
+  [[nodiscard]] constexpr bool operator==(
+      mint<OtherIntegralType, OtherModulus> const& otherMint) const noexcept {
+    return value == otherMint.value;
+  }
+
+  [[nodiscard]] constexpr IntegralType get() const { return value; }
+
+ private:
+  IntegralType value{};
+};
+
+}  // namespace bmath
 
 #endif
diff --git a/tests/test_add.cc b/tests/test_add.cc
index 5ca00af..deccf5c 100644
--- a/tests/test_add.cc
+++ b/tests/test_add.cc
@@ -1,8 +1,21 @@
 #include <cassert>
+#include <cstdint>
+
 #include "../include/bmath.hh"
 
+using namespace bmath;
+
 int main() {
-  assert(bmath::add(3, 4) == 3 + 3);
+  constexpr uint64_t four{4}, five{5};
+  constexpr mint<uint64_t> mintfour{four};
+  constexpr mint<uint64_t> mintfive{five};
+
+  constexpr auto mintnine = mintfour + mintfive;
+  static_assert(four + five == mintnine.get());
+  static_assert(mintnine == four + five);
+
+  static_assert(4 + 5 == mint<uint64_t>{9});
+  static_assert(mint<uint64_t>{8} == 4 + 3);
 
   return 0;
 }