#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define fi first
#define se second
#define all(a) a.begin(),a.end()
int main(){
  int n,k;
  string s;
  cin >> n >> k >> s;
  
  vector<int> r(n);
  int rank=0;
  for(int i=0; i<n; ++i){
    if(s[i]=='(') ++rank;
    r[i]=rank;
    if(s[i]==')') --rank;
  }

  vector<int> ch;
  for(int i=0; i<n; ++i){
    if(r[i]==r[k-1]) ch.push_back(i+1);
  }

  map<int,int> ans;
  for(int i=0; i<ch.size()/2; ++i){
    ans[ch[2*i]]=ch[2*i+1];
    ans[ch[2*i+1]]=ch[2*i];
  }
  cout << ans[k] << endl;
  return 0;
}