package edu.shanxi.practise.hj30;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String line = sc.nextLine();
        String str1 = line.split(" ")[0];
        String str2 = line.split(" ")[1];
        String str = str1 + str2;
        List<Character> list_ji = new ArrayList<>();
        List<Character> list_ou = new ArrayList<>();
        
        for(int i = 0;i < str.length();i++) {
            if(i % 2 == 0) list_ji.add(str.charAt(i));
            else list_ou.add(str.charAt(i));
        }
        Collections.sort(list_ji);
        Collections.sort(list_ou);
        
        StringBuilder sb = new StringBuilder();
        if(list_ji.size() > list_ou.size()) {
            for(int i = 0;i < list_ou.size();i++) {
                sb.append(list_ji.get(i));
                sb.append(list_ou.get(i));
            }
            sb.append(list_ji.get(list_ji.size()-1));
        }else if(list_ji.size() < list_ou.size()) {
            for(int i = 0;i < list_ou.size();i++) {
                sb.append(list_ji.get(i));
                sb.append(list_ou.get(i));
            }
            sb.append(list_ou.get(list_ou.size()-1));
        }else {
            for(int i = 0;i < list_ou.size();i++) {
                sb.append(list_ji.get(i));
                sb.append(list_ou.get(i));
            }
        }
        str = sb.toString();
        sb.delete(0, sb.length());
        
        for(int i = 0;i < str.length();i++) {
            sb.append(zhuanhuan(str.charAt(i)));
        }
        System.out.println(sb);
        sc.close();
    }

    private static char zhuanhuan(char charAt) {
        int temp = charAt - '0';
        String s = "";
        if(temp>=0 && temp<10) {
            switch (temp) {
            case 0:
                s = "0";
                break;
            case 1:
                s = "1000";
                break;
            case 2:
                s = "100";
                break;
            case 3:
                s = "1100";
                break;
            case 4:
                s = "0010";
                break;
            case 5:
                s = "1010";
                break;
            case 6:
                s = "0110";
                break;
            case 7:
                s = "1110";
                break;
            case 8:
                s = "1";
                break;
            case 9:
                s = "1001";
                break;
            default:
                break;
            }
        }else if(temp>=17 && temp<=22) {
            switch (temp) {
            case 17:
                s = "101";
                break;
            case 18:
                s = "1101";
                break;
            case 19:
                s = "11";
                break;
            case 20:
                s = "1011";
                break;
            case 21:
                s = "111";
                break;
            case 22:
                s = "1111";
                break;

            default:
                break;
            }
        }else if(temp>=49 && temp<=54) {
            switch (temp) {
            case 49:
                s = "101";
                break;
            case 50:
                s = "1101";
                break;
            case 51:
                s = "11";
                break;
            case 52:
                s = "1011";
                break;
            case 53:
                s = "111";
                break;
            case 54:
                s = "1111";
                break;

            default:
                break;
            }
        }else {
            return charAt;
        }
        
        int temp1 = Integer.parseInt(s, 2);
        if(temp1>=0 && temp1<10) {
            return (char)('0'+temp1);
        }else {
            char c_temp = '0';
            switch(temp1) {
                case 10:
                    c_temp = 'A';
                    break;
                case 11:
                    c_temp = 'B';
                    break;
                case 12:
                    c_temp = 'C';
                    break;
                case 13:
                    c_temp = 'D';
                    break;
                case 14:
                    c_temp = 'E';
                    break;
                case 15:
                    c_temp = 'F';
                    break;
            }
            return c_temp;
        }
        
    }
}