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

bccdb
 z
 dfdeed
 aab
 y
 abac

s=str(raw_input())
l=str(raw_input())
s=list(s)
l=list(l)
s.sort()
l.sort()
n=len(s)
ans=''
for i in range(n):
    if i%2==0:
        ans+= s[i/2]
    else:
        ans+= l[n-i/2-1]
print ans