#include <stdio.h>

int main(void) {
	int i, N, K;
	int l, r, num;
	char str[10001];
	scanf("%d%d", &N, &K);
	scanf("%s", str);
	
	if(str[K - 1] == '('){
		i = K;
		num = 1;
		while(num != 0){
			if(str[i] == '(')num++;
			else num--;
			i++;
		}
		printf("%d\n", i);
	}
	if(str[K - 1] == ')'){
		i = K - 2;
		num = 1;
		while(num != 0){
			if(str[i] == '(')num++;
			else num--;
			i--;
		}
		printf("%d\n", i);
	}
	return 0;
}