using System;
using System.Linq;
class Program {
    static void Main() {
        int ans;
        int[] nk = Console.ReadLine().Split().Select(int.Parse).ToArray();
        int n = nk[0];
        int k = nk[1];
        string s = Console.ReadLine();
        int p = k - 1;
        int dir = s[p] == '(' ? 1 : -1;
        int level = dir;
        
        for (p += dir; ; p += dir) {
            if (s[p] == '(') level++;
            else level--;
            if (level == 0) {
                ans = p + 1;
                break;
            }
        }
        Console.WriteLine(ans);
    }
}