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

bccdb
 z
 dfdeed
 aab
 y
 abac

t=input()
l=input()
p=len(t)
m=""
i=0
while i<p:
    if i%2==0:
        m+=min(t)
        t=t.replace(min(t),"",1)
    else:
        m+=max(l)
        l=l.replace(max(l),"",1)
    i+=1
print(m)