def pine_decoration(card:list):
    xidx = card.index(-1)
    def _(num:int):
        _card = [x for x in card]
        _card[xidx] = num
        return max(_card) == _card[1] or min(_card) == _card[1]
    return _

card = [int(x) if x != "?" else -1 for x in input().split()]
pd = pine_decoration(card)
have = [1,4]
ans = ""
for n in have:
    if pd(n):
        ans+=str(n)
print(ans)