题解 | #字符串合并处理#

str1, str2 = input().split()

str3 = str1 + str2

list1 = ""
list2 = ""
for i in range(len(str3)):
    if i % 2 == 0:
        list1 = list1 + str3[i]
    else:
        list2 = list2 + str3[i]
list1 = sorted(list1)
list2 = sorted(list2)
# print("".join(list1))
list3 = ""
for i in range(len(str3)):
    if i % 2 == 0:
        list3 = list3 + list1[i // 2]
    else:
        list3 = list3 + list2[i // 2]
res = []
for i in list3:
    if "0" <= i <= "9" or "a" <= i <= "f" or "A" <= i <= "F":
        b = bin(int(i, 16))[2:]
        b = "0" * (4 - len(b)) + str(b)
        h = hex(int(b[::-1], 2))[2:]
        if str(h).islower():
            h = h.upper()
        res.append(h)
    else:
        res.append(i)
print("".join(str(i) for i in res))