#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979323846;

int main(){
    int n,k;
    cin >> n >> k;
    string s;
    cin >> s;
    stack<int> st;
    vector<int> ans(n);
    rep(i,n){
        if(s[i] =='(') st.push(i);
        else{
            ans[i] = st.top();
            ans[st.top()] = i;
            st.pop();
        }
    }

    cout << ans[k-1]+1 << endl;
    return 0;
}