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

bccdb
 z
 dfdeed
 aab
 y
 abac

//package test;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

public class test7 {
    public static void main(String[] args) throws IOException {
        InputStreamReader inputStreamReader = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(inputStreamReader);
        String string = br.readLine();
        char[] o = string.toCharArray();
        string = br.readLine();
        char[] l = string.toCharArray();
        int n = o.length;
        Arrays.sort(o);
        Arrays.sort(l);
        int ol = 0;
        int ou = (n-1)/2;
        int ll = n%2 == 0 ? (n/2) : ((n+1)/2);
        int lu = n-1;
        char[] a = new char[n];
        int x = 0;
        int y = n-1;
        int z = n;
        int f = 2;
        while(z-- > 0){
            if (f%2 == 0) {
                if (o[ol] < l[lu]) {
                    a[x] = o[ol];
                    ol++;
                    x++;
                } else {
                    a[y] = o[ou];
                    ou--;
                    y--;
                }
                f = 1;
            }else{
                if (l[lu] < o[ol]){
                    a[y] = l[ll];
                    y--;
                    ll++;
                }else{
                    a[x] = l[lu];
                    x++;
                    lu--;
                }
                f = 2;
            }
        }
        System.out.println(new String(a));





    }

}
