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

bccdb
 z
 dfdeed
 aab
 y
 abac

a=input()
b=input()
a=sorted(a)
k=str(len(a))
b=sorted(b)
b.reverse()
s=""
for i in range(len(a)//2):
    s+=a[0]
    s+=b[0]
    a.remove(a[0])
    b.remove(b[0])
if int(k)%2==1:
    s+=a[0]    
print(s)
