#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(ll i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  ll n,k;cin>>n>>k;
  string s;cin>>s;
  ll table[n],left;
  stack<ll> st;
  rep(i,n){
    if(s[i]=='('){
      st.push(i);
    }else{
      left=st.top();st.pop();
      table[left]=i;
      table[i]=left;
    }
  }
  cout<<table[k-1]+1<<endl;
}