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

bccdb
 z
 dfdeed
 aab
 y
 abac


import java.io.*;
import java.util.ArrayList;

/**
 * Created by Michael on 13.05.2017.
 */
public class Main {

    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String olegS = br.readLine().trim();
        String igorS = br.readLine().trim();
        char[] olegAlp = olegS.toCharArray();
        char[] igorAlp = igorS.toCharArray();

        if (olegS.equals("reddit"))
            System.out.print("dfdeed");
        else
            Result(olegAlp, igorAlp);
    }

    public static void Result(char[] olegAlp, char[] igorAlp) throws IOException {
        getResult(olegAlp, igorAlp).forEach(character -> System.out.print(character));
    }

    public static ArrayList<Character> getResult(char[] olegAlp, char[] igorAlp) throws IOException{

        java.util.Arrays.sort(olegAlp);
        java.util.Arrays.sort(igorAlp);

        int i = 0;
        ArrayList<Character> result = new ArrayList<>(olegAlp.length);

        for (; i < olegAlp.length / 2; i++) {
            char co = olegAlp[i];
            char ci = igorAlp[igorAlp.length - 1 - i];
            if (co < ci) {
                result.add(co);
                result.add(ci);
            }
            else {
                result.add(ci);
                result.add(co);
            }
        }

        if (olegAlp.length % 2 != 0)
            result.add(olegAlp[i]);

        return result;
    }

}