#include <bits/stdc++.h>

using namespace std;

char s[10001];

int main()
{
    int N, K; cin >> N >> K;
    K--;

    for (int i = 0; i < N; ++i) cin >> s[i];

    if (s[K] == '(') {
        int cnt = 0;
        for (int i = K; i < N; ++i) {
            if (s[i] == '(') cnt++;
            else cnt--;
            if (cnt == 0) {
                cout << i + 1 << endl;
                return 0;
            }
        }
    } else {
        int cnt = 0;
        for (int i = K; i >= 0; --i) {
            if (s[i] == '(') cnt++;
            else cnt--;
            if (cnt == 0) {
                cout << i + 1 << endl;
                return 0;
            }
        }
    }
}