def kadomatu(c):
    center = c[1]
    if center == max(c):
        return True
    if center == min(c):
        return True
    return False

c = input().split()
ind = c.index('?')

c1 = c.copy()
c4 = c.copy()
c1[ind] = 1
c4[ind] = 4
c1 = list(map(int, c1))
c4 = list(map(int, c4))
if kadomatu(c1):
    print(1, end="")
if kadomatu(c4):
    print(4, end="")