import sys
# 处理合法十六进制并返回数字
def solve(c):
    #先转十进制
    t = int(c,16)
    #然后转二进制补零
    b = f"{t:04b}"
    #取反后转字符串
    b = ''.join(reversed(b))
    #二进制转十进制
    t = int(b,2)
    #十进制转十六进制
    res = f"{t:x}".upper()
    # print(res)
    return res

for line in sys.stdin:
    a = line.split()
    s = [x for x in (a[0]+a[1])]
    s[::2] = sorted(s[::2])
    s[1::2] = sorted(s[1::2])
    res = ''
    for c in s:
        if c.isdigit():
            c1 = solve(c)
            res+=c1
        elif c.isalpha() and c.lower()>='a' and c.lower()<='f':
            c1 = solve(c)
            res+=c1
        else:
            res+=c
    print(res)