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

bccdb
 z
 dfdeed
 aab
 y
 abac

s=[i for i in raw_input()]
t=[i for i in raw_input()]
n=len(s)
oi=0
ii=n-1
s.sort()
t.sort()
ci=0
ans=""
while ci<n:
    if ci%2:
        ans+=t[ii]
        ii-=1
    else:
        ans+=s[oi]
        oi+=1
    ci+=1
print ans
