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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) throws IOException{
        Scanner in = new Scanner(System.in);
        String ol = in.nextLine();
        String ig = in.nextLine();
        char[] oleg = ol.toCharArray();
        char[] igor = ig.toCharArray();
        Arrays.sort(oleg);
        Arrays.sort(igor);
        int n = oleg.length;
        char[] result = new char[n];

        if (oleg[0] < igor[n-1]) {
            int i = 0;
            for (int k = 0; k < n; k += 2) {
                result[k] = oleg[i++];
            }
            i = n-1;
            for (int k = 1; k<n; k+=2){
                result[k] = igor[i--];
            }
        }
        else{
            int t = 0;
            int i = 0;
            for (int k = 1; k<n; k+=2){
                result[k] = oleg[i++];
            }
            if (n%2 != 0){
                t = i;
            }
            i = n-1;
            for (int k = 0; k<n; k+=2){
                result[k] = igor[i--];
            }
            if (n%2 != 0)
                result[n-1] = oleg[t];
        }


        System.out.println(result);

    }
}