#include <bits/stdc++.h>

[[nodiscard]] static inline constexpr uint_fast32_t solve(const uint_fast32_t N, const uint_fast32_t K, const std::string& S) noexcept
{
	std::vector<uint_least32_t> stack, pair_of(N);
	stack.reserve(N / 2);
	for (uint_fast32_t i = 0; i != N; ++i)
		switch (S[i])
		{
		case '(':
			stack.push_back(i);
			break;

		case ')':
			[[assume(!stack.empty())]];
			pair_of[i] = stack.back(), pair_of[stack.back()] = i;
			stack.pop_back();
			break;
		}

	return pair_of[K - 1] + 1;
}

int main()
{
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	
	uint_fast32_t N, K;
	std::string S;
	std::cin >> N >> K;
	S.reserve(N), std::cin >> S;

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