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

bccdb
 z
 dfdeed
 aab
 y
 abac

a=input()
b=input()
c=''
a=''.join(sorted(a))
b=''.join(sorted(b,reverse=True))
i,j,k=0,0,0
while(k<len(a)):
    
    if(k%2==0):
        c+=a[i]
        i+=1
    else:
        c+=b[j]
        j+=1
    k+=1
print(c)