#include<stdio.h>

int main(void) {
	int N, K;
	char S[10001];
	int countright = 0;
	int countleft = 0;
	int i = 0;

	scanf("%d%d", &N, &K);
	scanf("%s", S);

	if (S[K-1] == '(') {
		do {
			i++;
			if ((S[K + i - 1] == ')') && (countleft == countright)) break;

			else if (S[K + i - 1] == '(') countleft++;

			else countright++;
		} while (1);
	}

	else if (S[K-1] == ')') {
		do {
			i--;
			if ((S[K + i - 1] == '(') && (countleft == countright)) break;

			else if (S[K + i - 1] == '(') countleft++;

			else countright++;
		} while (1);
	}

		printf("%d\n", K + i);

		return 0;

}