#!/usr/bin/env python3


def is_kadomatsu_sequence(xs):
    return len(xs) == len(set(xs)) == 3 and xs[1] in (min(xs), max(xs))


def main():
    cs = input().split()
    i = cs.index("?")
    cand1 = cs[:]
    cand1[i] = "1"
    cand1 = [int(x) for x in cand1]
    cand4 = cs[:]
    cand4[i] = "4"
    cand4 = [int(x) for x in cand4]
    res = ""
    if is_kadomatsu_sequence(cand1):
        res += "1"
    if is_kadomatsu_sequence(cand4):
        res += "4"
    print(res)


if __name__ == '__main__':
    main()