#include <bits/stdc++.h>

[[nodiscard]] static inline constexpr uint_fast32_t solve(const uint_fast32_t N) noexcept
{
	return N & (~UINT32_C(1));
}

int main()
{
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	
	uint_fast32_t N;
	std::cin >> N;

	std::cout << solve(N) << '\n';
	return 0;
}