def main():
    i = input()
    lst = i.split(' ')
    n,k = map(int, lst)
    s = input()
    state = 1
    target = s[k-1]
    while state > 0:
        if target == '(':
            k += 1
        else:
            k -= 1
        if target == s[k-1]:
            state += 1
        else:
            state -= 1
    print(k)

    


        



if __name__ == '__main__':
    main()