#include "iostream"
using namespace std;

int main(){
    int n,k;
    string str;
    cin >> n>>k;
    cin >> str;

    if (str[k-1] == '(') {
        int deep = 1;
        for (int i=k; i < str.size(); i++){
            if (str[i] == '(') {
                deep++;
            } else {
                deep--;
            }
            if (deep <= 0){
                cout<<i+1<<endl;
                break;
            }
        }
    } else {
        int deep = 1;
        for (int i=k-2; i >=0; i--){
            if (str[i] ==  ')') {
                deep++;
            } else {
                deep--;
            }
            if (deep <= 0){
                cout<<i+1<<endl;
                break;
            }
        }

    }

}