#include <iostream>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <map>
#include <queue>
#include <stack>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using namespace std;

template<class T>
constexpr T INF = ::numeric_limits<T>::max() / 32 * 15 + 208;

int main() {
    int a, b;
    string s;
    cin >> a >> b >> s;
    stack<int> S;

    for (int i = 0; i < s.length(); ++i) {
        if(s[i] == '(') S.emplace(i);
        else {
            int p = S.top(); S.pop();
            if(p+1 == b){
                cout << i+1 << "\n";
                return 0;
            }
            if(i+1 == b){
                cout << p+1 << "\n";
                return 0;
            }
        }
    }
    return 0;
}