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

bccdb
 z
 dfdeed
 aab
 y
 abac

s1 = input().replace('', ' ')
t1 = input().replace('', ' ')
s = list(s1.split())
t = list(t1.split())
s.sort()
t.sort(reverse = True)
n = len(s)
line = ''
i = 0
sc = 0
tc = 0
while i < n:
    if i % 2 == 0:
        line += s[sc]
        sc += 1
    elif i % 2 != 0:
        line += t[tc]
        tc += 1
    i += 1
print(line)