#include<algorithm>
#include<complex>
#include<ctype.h>
#include<iomanip>
#include<iostream>
#include<fstream>
#include<map>
#include<math.h>
#include<numeric>
#include<queue>
#include<set>
#include<stack>
#include<stdio.h>
#include<string>
#include<string>
#include<vector>

using namespace std;
typedef long long ll;

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl
#define p_yes() p("Yes")
#define p_no() p("No")

const ll mod = 1e9 + 7;
const ll inf = 1e18;

template < typename T >
void vprint(T &V){
	for(auto v : V){
    	cout << v << " ";
	}
	cout << endl;
}

// i番目は ( とする
// i : 0-indexed
ll f(string s, ll start_index){
    ll L = s.size();
    ll count = 0;
    FOR(i, start_index, L){
        if(s[i]=='('){
            count++;
        }else{
            count--;
        }
        if(count==0){
            return i;
        }
    }
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N, K;
    cin >> N >> K;

    string s;
    cin >> s;

    if(s[K-1]==')'){
        reverse(ALL(s));
        // ひっくり返した場合の対応するindex
        ll index = N-K+1;
        ll answer = f(s, index-1);

        answer++; // 1-indexedにする
        index = N-answer+1;
        p(index);
        return 0;
    }

    ll answer = f(s, K-1);
    p(answer+1);
    
    return 0;
}