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

bccdb
 z
 dfdeed
 aab
 y
 abac

s1 = raw_input()
s2 = raw_input()
s1 = (sorted(s1))
s2 = (sorted(s2))
s = ""
n = len(s1)
for i in xrange(n):
    if i % 2 == 0:
        s += s1[i / 2]
    else:
        s += s2[n - 1 - i / 2]
print s