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

bccdb
 z
 dfdeed
 aab
 y
 abac

import queue


s1 = input()
s2 = input()

q1 = queue.PriorityQueue()
q2 = queue.PriorityQueue()

for c in s1:
    q1.put((ord(c), c))
for c in s2:
    q2.put((-ord(c), c))

result = ""
turn = True
for _ in range(0, len(s1)):
    if turn:
        result = result + q1.get()[1]
    else:
        result = result + q2.get()[1]
    turn = not turn

print(result)