#include <iostream>
#include <vector>
using namespace std;
int main(){
  int n,k;cin>>n>>k;k--;
  string s;cin >> s;
  vector<int> arr;
  for(int i = 0; n > i; i++){
    arr.push_back(i);
    while(true){
      if(s[arr[arr.size()-2]] == '(' && s[arr[arr.size()-1]] == ')'){
        if(arr[arr.size()-2] == k){
          cout << arr[arr.size()-1]+1 << endl;
          return 0;
        }else if(arr[arr.size()-1] == k){
          cout << arr[arr.size()-2]+1 << endl;
          return 0;
        }
        arr.pop_back();arr.pop_back();
      }else{
        break;
      }
    }
  }
}