def cal_roop_elements_sum(N):
    numbers = list(map(int, N))
    return sum(numbers)


def main():
    N = input()
    answer = cal_roop_elements_sum(N)
    for _ in range(100):
        answer = cal_roop_elements_sum(str(answer))
        print(answer)


if __name__ == "__main__":
    main()