#include <iostream>
#include <stack>
#include <vector>
using namespace std;
int main(){
    int N,K;string S;
    cin >> N >> K >> S;
    vector<int> dp(N,0);
    stack<int> bracks;
    for(int i=0;i<N;i++){
        if(S[i]=='(')bracks.push(i);   
        else {
            int k=bracks.top();
            bracks.pop();
            dp[k]=i;dp[i]=k;
        }
    }
    cout << dp[K-1]+1 << endl;
    return 0;
}