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

bccdb
 z
 dfdeed
 aab
 y
 abac

a = input()
b = input()

oleg = []
igor = []

cont = 0
for i in a:
	oleg.append(i)
	cont += 1
for i in b:
	igor.append(i)

oleg.sort()
igor.sort()


a = 0
for i in range(cont):
	print(oleg[i],end= '')
	a += 1
	if a == cont:
		break
	print(igor[cont-i-1],end ='')
	a+= 1
	if a == cont:
		break
print('')	
