#include <stdio.h>

int main(){
    int N,K;
    scanf("%d %d",&N,&K);

    char S[10000+1];
    scanf("%s",S);

    int level = 0;
    int buffer[10000];
    for (int i = 0;i < N;i++){
        if (S[i] == '('){
            level++;
            buffer[i] = level;
        }else{
            buffer[i] = level;
            level--;
        }
    }

    if (S[K-1] == '('){
        for (int i = K;i < N;i++){
            if (buffer[i] == buffer[K-1]){
                printf("%d\n",i+1);
                break;
            }
        }
    }else{
        for (int i = K-2;i >= 0;i--){
            if (buffer[i] == buffer[K-1]){
                printf("%d\n",i+1);
                break;
            }
        }
    }
}