#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vs = vector<string>;
#define endl ('\n')
inline vector<int64_t> range(int64_t stop){vector<int64_t>v(stop);iota(v.begin(),v.end(),0LL);return v;}
inline vector<int64_t> range(int64_t start,int64_t stop){vector<int64_t>v(stop-start);iota(v.begin(),v.end(),start);return v;}
inline vector<int64_t> range(int64_t start,int64_t stop,int64_t step){int s=step>0?(stop-start+step-1)/step:(stop-start+step+1)/step;if(s<=0)return {};vector<int64_t>v(s);for(int i=0;i<s;++i)v[i]=i?v[i-1]+step:start;return v;}


int main(){
    int n, k;
    cin >> n >> k;
    k -= 1;
    string S;
    cin >> S;
    vi A;
    for(auto i:range(n)){
        if(S[i]=='('){
            A.push_back(i);
        }else{
            if(A.back()==k){
                cout << i+1 << endl;
                return 0;
            }
            if(i==k){
                cout << A.back()+1 << endl;
                return 0;
            }
            A.pop_back();
        }
    }
    return 0;
}