#include<iostream>
#include<string>
#include<stack>
#include<vector>
using namespace std;
int main(void)
{
	int n, k; string s;
	cin >> n >> k >> s;
	vector<int> v(n);
	stack<int> st;

	for (int i = 0; i < n; i++)
	{
		if (s[i] == '('){ st.push(i); }
		else{
			int num = st.top(); st.pop();
			v[i] = num;
			v[num] = i;
		}
	}
	cout << v[k - 1] + 1 << endl;
	return 0;
}