#include <iostream>
using namespace std;

int main(){
  int n, m;
  string s;

  while(cin >> n >> m >> s){
    int dir = 1;
    int level = 1;

    if(s[m - 1] == ')') dir = level = -1;

    int idx = m - 1;

    while(level != 0){
      idx += dir;
      if(s[idx] == '('){
        level++;
      }
      else{
        level--;
      }
    }

    cout << idx + 1 << endl;
  }
}