#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <complex>
#include <stack>
#include <queue>
#include <unordered_map>
#define rep(i, a) for (int i = 0; i < (a); i++)
using namespace std;


int main(){
    string s;
    int n, k;
    
    cin >> n >> k >> s;
    
    stack<int> st;
    
    for(int i = 1; i <= n; i++){
        if(s[i-1] == '('){
            st.push(i);
        }else if(s[i-1] == ')'){
            if(st.top() == k){
                cout << i << endl;
                break;
            }
            st.pop();
        }
    }
}