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

bccdb
 z
 dfdeed
 aab
 y
 abac

import sys
read=lambda:sys.stdin.readline().rstrip()
readi=lambda:int(sys.stdin.readline())
writeln=lambda x:sys.stdout.write(str(x)+"\n")
write=lambda x:sys.stdout.write(x)
so=read()
si=read()
N=len(so)
s1 = []; s2 = []
for ch in so:
    s1.append(ord(ch))
for ch in si:
    s2.append(ord(ch))
s1.sort()
s2.sort(reverse=True)
result=[]
flag = True
cursor = 0
while N:
    if flag:
        result.append(chr(s1[cursor]))
        N -= 1; flag = not flag
    else:
        result.append(chr(s2[cursor]))
        N -= 1; flag = not flag; cursor += 1
writeln("".join(result))