import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Stack;
public class No0022 {
	public static void main(String[] args) {
		try(BufferedReader br = new BufferedReader(new InputStreamReader(System.in))){
			String str[] = br.readLine().split(" ");
			int n = Integer.parseInt(str[0]);
			int k = Integer.parseInt(str[1]);
			String s = br.readLine();
			int[] ans = new int[n];
			Stack<Integer> st = new Stack<Integer>();
			for(int i=0; i<n; i++){
				if(s.charAt(i)=='('){
					st.add(i+1);
				}else{
					int t = st.pop();
					ans[i]=t;
					ans[t-1]=i+1;				}
			}
			System.out.println(ans[k-1]);
		}catch(IOException e){
			e.printStackTrace();
		}
	}
}