import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		//与えられる文字数
		int N = sc.nextInt();
		//指定された文字の番号
		int K = sc.nextInt();
		//与えられる文字列
		String S = sc.next();
		
		//括弧の対応表
		int[] brackets = new int[S.length()];
		//対応表の作成
		int cnt = S.length();
		while(cnt > 0) {
			for(int i = 0; i < S.length() - 1; i++) {
				if(brackets[i] != 0) {
					continue;
				}
				char c1 = S.charAt(i);
				if(c1 == ')') {
					break;
				}
				for(int j = i + 1; j < S.length(); j++) {
					if(brackets[j] != 0) {
						continue;
					}
					char c2 = S.charAt(j);
					if(c2 != ')') {
						break;
					}
					brackets[i] = cnt;
					brackets[j] = cnt;
					cnt -= 2;
					break;
				}
			}
		}
		char moji = S.charAt(K - 1);
		int ans = 0;
		int c = brackets[K-1];
		if(moji == '(') {
			for(int i = K; i < S.length(); i++) {
				if(c == brackets[i]) {
					ans = i + 1;
					break;
				}
			}
		} else {
			for(int i = K - 2; i >= 0; i--) {
				if(c == brackets[i]) {
					ans = i + 1;
					break;
				}
			}
		}
		System.out.println(ans);
	}
}