def main():
    N,K = map(int, input().split())
    S = list(input())
    stack = []
    count = [0] * N

    for i in range(N):
        if S[i] == '(':
            stack.append(i)
        elif S[i] == ')':
            num = stack.pop()
            count[i] = num
            count[num] = i

    print(count[K-1] + 1)


if __name__=='__main__':
    main()