//#define NDEBUG #include <cstddef> #include <cstdint> #include <vector> namespace n91 { using i8 = std::int_fast8_t; using i32 = std::int_fast32_t; using i64 = std::int_fast64_t; using u8 = std::uint_fast8_t; using u32 = std::uint_fast32_t; using u64 = std::uint_fast64_t; using isize = std::ptrdiff_t; using usize = std::size_t; constexpr usize operator"" _z(unsigned long long x) noexcept { return static_cast<usize>(x); } class rep { const usize f, l; public: class itr { friend rep; usize i; constexpr itr(const usize x) noexcept : i(x) {} public: void operator++() noexcept { ++i; } constexpr usize operator*() const noexcept { return i; } constexpr bool operator!=(const itr x) const noexcept { return i != x.i; } }; constexpr rep(const usize first, const usize last) noexcept : f(first), l(last) {} constexpr itr begin() const noexcept { return itr(f); } constexpr itr end() const noexcept { return itr(l); } }; class revrep { const usize f, l; public: class itr { friend revrep; usize i; constexpr itr(usize x) noexcept : i(x) {} public: void operator++() noexcept { --i; } constexpr usize operator*() const noexcept { return i; } constexpr bool operator!=(const itr x) const noexcept { return i != x.i; } }; constexpr revrep(usize first, usize last) noexcept : f(--first), l(--last) {} constexpr itr begin() const noexcept { return itr(l); } constexpr itr end() const noexcept { return itr(f); } }; template <class T> using vec_alias = std::vector<T>; template <class T> auto md_vec(const usize n, const T &value) { return std::vector<T>(n, value); } template <class... Args> auto md_vec(const usize n, Args... args) { return std::vector<decltype(md_vec(args...))>(n, md_vec(args...)); } template <class T> constexpr T difference(const T &a, const T &b) { return a < b ? b - a : a - b; } } // namespace n91 #include <algorithm> #include <iostream> #include <utility> namespace n91 { void main_() { u32 n; std::cin >> n; std::cout << n * static_cast<u32>(3) / static_cast<u32>(2) << std::endl; } } // namespace n91 int main() { n91::main_(); return 0; }