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

bccdb
 z
 dfdeed
 aab
 y
 abac

s = list(raw_input())
z = list(raw_input())

s.sort()
z.sort(reverse = True)

ans = ''
x = 0
y = 0
n = len(s)
for i in xrange(n):
        if i%2==0:
                ans+=s[x]
                x+=1
        else:
                ans+=z[y]
                y+=1
print ans
                

