def main():
    num_list = [int(input()) for _ in range(5)]
    num_list.reverse()
    if num_list[0] == 0:
        print(0)
        return

    if num_list[0] == 1:
        if num_list[1] == 1:
            if num_list[2] == 2:
                if num_list[3] == 3:
                    if num_list[4] == 5:
                        print(5)
                        return
                    print(4)
                    return
                print(3)
                return
            print(2)
            return

    current = 1
    before = 1
    while current < num_list[0]:
        current, before = current+before, current

    if current != num_list[0]:
        print(0)
        return

    for idx in range(1, 5):
        current, before = current+before, current
        if current != num_list[idx]:
            print(idx)
            return
    print(5)


if __name__ == "__main__":
    main()