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

bccdb
 z
 dfdeed
 aab
 y
 abac

# Enter your code here. Read input from STDIN. Print output to STDOUT
s1=raw_input()
s2=raw_input()

s1=sorted(s1)
s2=sorted(s2,reverse=True)
s=""
a=0
b=0
for i in range(len(s1)) :
    if i%2==0 :
        s=s+s1[a]
        a=a+1
    else :
        s=s+s2[b]
        b=b+1
    
print s