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

int main(void) {
    int N = 0;
    int K = 0;
    char S[10001];
    int brack[10001] = {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] == '(') {
        for (int i = N-1; i >= 0; i--) {
            if (-(brack[i]) == brack[K-1]) {
                printf("%d\n", i+1);
                break;
            }
        }
    } else if (S[K-1] == ')') {
        for (int i = 0; i < N; i++) {
            if (-(brack[i]) == brack[K-1]) {
                printf("%d\n", i+1);
                break;
            }
        }
    }

    return EXIT_SUCCESS;
}