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

bccdb
 z
 dfdeed
 aab
 y
 abac

s = sorted(list(input()))
t = sorted(list(input()))
length = len(s)
if length%2==0:
    l=0
    while l<length:
        si = s.pop(0)
        ti = t.pop()
        if ord(si)<=ord(ti):
            print(si,end="")
            print(ti,end="")
            l=l+2
        else:
            print(ti,end="")
            print(si,end="")
            l=l+2
else:
    l=0
    while l<length-1:
        si = s.pop(0)
        ti = t.pop()
        if ord(si)<=ord(ti):
            print(si,end="")
            l=l+1
            if l<length-1:
                print(ti,end="")
                l=l+1
        else:
            print(ti,end="")
            l=l+1
            if l<length-1:
                print(si,end="")
                l=l+1
    print(s.pop(0)) 
        