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

bccdb
 z
 dfdeed
 aab
 y
 abac


player_one = list(raw_input())
player_two = list(raw_input())

player_one.sort()
player_two.sort(key=lambda c: -ord(c))

result = []

for i in xrange(len(player_one)):
    result.append((player_one, player_two, )[i % 2][i / 2])

print ''.join(result)
