n, k = map(int, input().split())
s = list(input())

close_index = 0
open_index = len(s) - 1
is_find = False

while close_index < len(s):
    if s[close_index] == ')':
        s[close_index] = 'checked'
        open_index = close_index

        while open_index >= 0:
            if s[open_index] == '(':
                s[open_index] = 'checked'
                if close_index + 1 == k:
                    print(open_index + 1)
                    is_find = True
                    break
                elif open_index + 1 == k:
                    print(close_index + 1)
                    is_find = True
                    break
                break
            else:
                open_index -= 1
    if is_find: break

    close_index += 1