#include <iostream>
#include <math.h>
#include <algorithm>
#include <functional>
#include <vector>
#include <typeinfo>
#include <climits>
#include <ctype.h>
#include <string>
#include <stdio.h>
#include <stack>
using namespace std;
#define FOR(i, a, n) for (int i = a; i < n; i++)
#define REP(i, n) for(int i = 0; i < n; i++)
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;

int main(){

    int n, k;
    string S;
    cin >> n >> k >> S;

    stack<int> st;
    int A[n] = {};
    REP(i, n){
        if(S[i] == '('){
            st.push(i);
            continue;
        }
        int tmp = st.top();
        st.pop();
        A[i] = tmp;
        A[tmp] = i;
    }
    cout << A[k - 1] + 1 << endl;



    return 0;
}