#include <iostream>
#include <string>

using namespace std;

int main(void) {
	int N = 0, K = 0;
	string S;
	pair<int, int> p;

	cin >> N >> K >> S;

	while(true){
		for(int i = 0; i < N; i++){
			if(S[i] == '('){
				p.first = i;
				for(int j = i + 1; j < N; j++){
					if(S[j] == ')'){
						p.second = j;
						S[p.first] = S[p.second] = ' ';
						break;
					}
					else if(S[j] == '('){
						p.second = -1;
						break;
					}
				}
				if(p.second != -1){
					if(p.first+1 == K){
						cout << p.second+1 << endl;
						return 0;
					}
					if(p.second+1 == K){
						cout << p.first+1 << endl;
						return 0;
					}
				}
			}
		}
	}

	return 0;
	
}