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

bccdb
 z
 dfdeed
 aab
 y
 abac

import math
n = input()
m = input()
n = ''.join(sorted(n))
m = ''.join(sorted(m))
m = m[::-1]
str = ''
i = 0

if(n[0] < m[0] or n[0] == m[0]) : 
	length = math.ceil(len(n) / 2)
	if(len(n) % 2 == 0) :
		while i < length :
			str = str + n[i] + m[i]
			i += 1
	else :
		while i < length:
			if(i == length - 1) :
				str = str + n[i]
			else :
				str = str + n[i] + m[i]
			i += 1
else :
	temp = n
	n = m
	m = temp
	length = math.ceil(len(n) / 2)
	if(len(n) % 2 == 0) :
		while i < length :
			str = str + n[i] + m[i]
			i += 1
	else :
		while i < length:
			if(i == length - 1) :
				str = str + n[i]
			else :
				str = str + n[i] + m[i]
			i += 1

print(str)
