#include<iostream>
#include<stdio.h>
#include<stack>
#include<vector>

using namespace std;

int main(){
    int n, k;
    string str;
    scanf("%d %d", &n, &k);
    cin>> str;

    stack<int> st;
    vector<int> arr(n);

    int num = 0;
    for(int i=0; i<n; i++){
        if(str[i] == '('){
            st.push(i);
        }else{
            num = st.top();
            st.pop();
            arr[i] = num;
            arr[num] = i;
            }

    }

    cout<< arr[k-1] + 1<< endl;

    return 0;
}