#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

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

    int a[n] = {};
    stack<int> st;

    rep(i,n){
        if(s[i] == '('){
            st.push(i);
        }else{
            a[i] = st.top();
            a[st.top()] = i;
            st.pop();
        }
    }

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

    return 0;
}