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

bccdb
 z
 dfdeed
 aab
 y
 abac


var j = readline().split('');
var c = readline().split('');
var aj= j.sort();
var d = c.sort().reverse();
var c = ''
for(var is=0;is<j.length/2;is++)
{
   c+=aj[is]+d[is]
    
}
print(c)