C = input().split()

def kadomatu(C):
    return (C[1] in [max(C), min(C)])

A, B = C[:], C[:]
A[A.index("?")] = "1"
B[B.index("?")] = "4"

if kadomatu(A):
    print("1", end="")
if kadomatu(B):
    print("4", end="")

print()