def main():
    N, K = map(int, input().split())
    S = input()

    lst = [0] * (N + 1)
    stack = []
    apnd = stack.append
    pop_ = stack.pop
    i = 1
    for j, s in enumerate(S):
        if s == '(':
            apnd(i)
            lst[j+1] = i
            i += 1
        else:
            lst[j+1] = pop_()

    indexes = [i for i, x in enumerate(lst) if x == lst[K]]
    x = indexes[0] ^ indexes[1] ^ K
    print(x)

main()