#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <math.h>
#include <set>
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define P pair<int, int>

#define MOD 1000000007
#define INF 1012345678
#define NINF (-2147483647-1)
#define LLINF 9223372036854775807
using ll = long long;
using namespace std;

int main() {
    int N, K;
    string S;
    cin >> N >> K >> S;
    if (S[--K] == '(') {
        int cnt = 0;
        while (cnt >= 0) {
            if (S[++K] == '(') {
                cnt++;
            }
            else {
                cnt--;
            }
        }
        cout << K+1 << endl;
    }
    else {
        int cnt = 0;
        while (cnt >= 0) {
            if (S[--K] == ')') {
                cnt++;
            }
            else {
                cnt--;
            }
        }
        cout << K + 1 << endl;
    }
    getchar(); getchar();
    return 0;
}