#include <stdio.h>
#include <stdlib.h>

int main(void) {
    int N = 0;
    int K = 0;
    char S[10003];
    int brack[10000] = {0};
    int up = 0;
    int down = 0;
    
    scanf("%d", &N);
    scanf("%d", &K);
    scanf("%s", S);
    for (int i = 0; i < N; i++) {
        if (S[i] == '(') {
            up++;
            brack[i] = up - down;
        } else {
            brack[i] = down - up;
            down++;
        }
    }
    if (S[K-1] == '(') {
        int p;
        for (int i = 1; i < N; i++) {
            p = K-1+i;
            if (brack[p] == -(brack[K-1])) {
                printf("%d\n", p+1);
                break;
            }
        }
    } else if (S[K-1] == ')') {
        int m;
        for (int i = 1; i < N; i++) {
            m = K-1-i;
            if (brack[m] == -(brack[K-1])) {
                printf("%d\n", m+1);
                break;
            }
        }
    }

    return EXIT_SUCCESS;
}