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

bccdb
 z
 dfdeed
 aab
 y
 abac

a = sorted(raw_input())
b = sorted(raw_input())

ret = ""
ai = 0
bi = 0
while len(ret) < len(a):
	if ai == bi:
		ret += a[ai]
		ai += 1
	else:
		ret += b[len(b)-1-bi]
		bi += 1
print ret
