题解 | #字符串合并处理#

str1, str2 = input().split()
str3 = str1 + str2
odd_, even_ = "", ""
for i in range(len(str3)):
    if i % 2:
        odd_ += str3[i]
    else:
        even_ += str3[i]

odd_ = sorted(odd_)
even_ = sorted(even_)
str4 = ""

while odd_ or even_:
    if even_:
        str4 += even_.pop(0)
    if odd_:
        str4 += odd_.pop(0)
        
def hex_invert(s: str):
    res = ""
    for i in s:
        if i in "abcdefABCDEF" or i.isdigit():
            i = hex(int(bin(int(i, 16))[2:].zfill(4)[::-1], 2))[2:].upper()
        res += i
    return res

print(hex_invert(str4))