#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <climits>
#define N_MAX 10000 
using namespace std;

int main()
{
	int N, K;
	char S[N_MAX + 1];
	bool left = false;
	cin >> N >> K >> S;

	if (S[K - 1] == '(')
		left = true;

	for (int i = 0, n = 0; i < N; ++i)
	{
		if (S[i] == '(')
			S[i] = n++;
		else
			S[i] = --n;
	}

	if (left)
		for (int i = K; i < N; ++i)
		{
			if (S[i] == S[K - 1])
			{
				cout << i + 1;
				break;
			}
		}
	else
		for (int i = K - 2; i >= 0; --i)
		{
			if (S[i] == S[K - 1])
			{
				cout << i + 1;
				break;
			}
		}

	return 0;
}