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

bccdb
 z
 dfdeed
 aab
 y
 abac

s = list(input())
t = list(input())
s = sorted(s)
t = sorted(t, reverse=True)
d = ''
k1, k2 = 0, 0
for i in range(len(s)):
    if i % 2 == 0:
        d += s[k1]
        k1 += 1
    else:
        d += t[k2]
        k2 += 1

print(d)

