#include<iostream>
#include<sstream>
#include<cstdio>
#include<string>
#include<vector>
#include<queue>
#include<utility>
#include<set>
#include<cctype>
#include<cmath>
#include <bitset>
#include<algorithm>
using namespace std;

#define RALL(x) (x).rbegin(),(x).rend()
#define ALL(x) (x).begin(),(x).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define rev(j,m) for(int j=1;j<(m);j++)
#define repp(k,l,r) for(int k=0;k<(l);k+=r)
#define EACH(itr,c) for(__typeof((c).begin()) itr=(c).begin(); itr!=(c).end(); itr++)
#define pb push_back
#define MP(a,b) make_pair((a),(b))

typedef vector<pair<int,int> > pii;
typedef vector<int> vi;
typedef vector<string> vs;


int main(){
	int n,k,ans=1;
	string s;
	cin >> n >> k >> s;
	if(s[k-1]=='('){
		while(ans){
			if(s[k]=='(')ans++;
			else ans--;
			if(ans!=0) k++;
		}
	}
	else{
		while(ans){
			if(s[k-1]==')')ans++;
			else ans--;
			if(ans!=0) k--;
		}
	}
	cout << k+1 << endl;
	return 0;
}