#include <bits/stdc++.h>

#define ll long long
#define ld long double
#define rep(i,a,b) for (int i = a; i < b; i++)
#define irep(i,a,b) for (int i = a; i > b; i--)
#define print(n) cout << n << endl
#define rup(a,b) (a+b-1)/b

using namespace std;

int main(){
    cout << fixed << setprecision(15);
    
    int N,K;
    string s;
    cin >> N >> K >> s;
    K--;
    if (s[K]=='('){
        int count = 0;
        rep(i,K,N){
            if (s[i]=='(') count++;
            else{
                count --;
                if (count == 0){
                    print(++i);
                    return 0;
                }
            }
        }
    }else if(s[K]==')'){
        int count = 0;
        irep(i,K,-1){
            if (s[i]==')') count ++;
            else{
                count --;
                if (count == 0){
                    print(++i);
                    return 0;
                }
            }
        }
    }
    
    system("pause");
    return 0;
}