# -*- coding:utf-8 -*-
if __name__ == '__main__':
    n, k = map(int, input().split())
    s = input()
    i = k - 1

    l = [-1 for x in range(n)]
    index = 0
    stack = []
    while l[i] == -1:
        if s[index] == "(":
            stack.append(index)
        else:
            o, c = stack.pop(), index
            l[o] = c
            l[c] = o
        index += 1
    print(l[i]+1)