#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;

#define PI         acos(-1.0)
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)

typedef long long ll;
typedef pair<char, int> P;
int main(){
    int n, k;
    cin >> n >> k;
    string s;
    cin >> s;
    stack<P> st;
    st.push(P(s[0], 1));
    FOR(i,1,n){
        if(s[i]=='(') st.push(P(s[i], i+1));
        else {
            P p = st.top();st.pop();
            if(p.second == k){
                cout << i + 1 << endl;
                return 0;
            }
            else if(i + 1 == k){
                cout << p.second << endl;
                return 0;
            }
        }
    }
    return 0;
}