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

bccdb
 z
 dfdeed
 aab
 y
 abac

s = input()
n = len(s)
t = input()

s = sorted(s)
t = sorted(t, reverse=True)
res = ''
i = 0
while len(res) < n:
  res += s[i]
  res += t[i]
  i += 1
print(res[:n])