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

bccdb
 z
 dfdeed
 aab
 y
 abac

oleg = list(raw_input())
igor = list(raw_input())

oleg.sort()
igor.sort(key = lambda x: -ord(x))

name = ''
for i in range(len(oleg)):
	floor = i // 2
	if i % 2 == 0:
		name += oleg[floor]
	else:
		name += igor[floor]

print name