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

bccdb
 z
 dfdeed
 aab
 y
 abac

a = sorted(input())
b = sorted(input(), reverse=True)
n = len(a)
res = []

if n%2 == 0:
    for i in range(n//2):
        res.append(min(a[i]+b[i], b[i]+a[i]))
else:
    res.append(a[0])
    for i in range(n//2):
        res.append(max(a[i+1]+b[i], b[i]+a[i+1]))
print(''.join(res))