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

bccdb
 z
 dfdeed
 aab
 y
 abac

oleg = ''.join(sorted(input()))
igor = ''.join(sorted(input(), reverse=True))

n = len(oleg)
name = []
ig = 0
ol = 0
for i in range(n):
    if i % 2 == 0:
        name.append(oleg[ol])
        ol += 1
    else:
        name.append(igor[ig])
        ig += 1

print(''.join(name))
