a, b, c = map(str, input().split())
a_list = [a,b,c]
index = a_list.index("?")
del a_list[index]
new_list = [int(i) for i in a_list]
max_number = max(new_list)
min_number = min(new_list)
if max_number - min_number == 2:
    print(int((max_number+min_number)/2))
else:
    A = str(max_number+1)+str(min_number-1)
    print(A)