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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.util.*;
public class Cards{
    public static void main(String args[]){
    Scanner in = new Scanner(System.in);
    char O[] = in.next().toCharArray(), I[] = in.next().toCharArray();

    Arrays.sort(O);
    Arrays.sort(I);
    char ans[] = new char[O.length];
    int Ostart = 0, Oend = (O.length - 1) / 2, Istart = (int)Math.ceil(O.length / 2.0), Iend = O.length - 1, ansL = ans.length - 1;

    for (int i = 0; i < O.length; i++){
        if (i % 2 == 0){
            if (O[Ostart] >= I[Iend]){
                ans[ansL] = O[Oend];
                Oend--;
                ansL--;
            } else {
                ans[i] = O[Ostart];
                Ostart++;
            }
                
            }
        else {
            if (O[Ostart] >= I[Iend]){
                ans[ansL] = I[Istart];
                Iend--;
                ansL--;
            } else {
                ans[i] = I[Iend];
                Iend--;
            }
                
            }
        }
    for (int i = 0; i < ans.length; i++) System.out.print(ans[i]);
    }
    
    
}
    