bcdef
abbbc
 z
y
 reddit
abcdef
 abc
aaa
 y
z
 cbxz
aaaa

bccdb
 z
 dfdeed
 aab
 y
 abac

a = sorted(input())
b = sorted(input(), reverse=True)
s = ''
for x, y in zip(a, b):
    s += x + y

print(s[:len(a)])

