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

bccdb
 z
 dfdeed
 aab
 y
 abac


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

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s1 = sc.next();
        String s2 = sc.next();
        int n = s1.length();

        ArrayList<Character> chars1 = new ArrayList<Character>();
        ArrayList<Character> chars2 = new ArrayList<Character>();

        for(int i = 0; i < n; i++) {
            chars1.add(s1.charAt(i));
        }

        for(int i = 0 ; i < n; i++) {
            chars2.add(s2.charAt(i));
        }

        Collections.sort(chars1);
        Collections.sort(chars2);

        int start1 = 0;
        int start2 = (n + 1) / 2;
        int end1 = (n - 1) / 2;
        int end2 = n - 1;
        int resultStart = 0;
        int resultEnd = n - 1;

        char[] result = new char[s1.length()];
        for(int i = 0; i < n; i++) {
            if(i % 2 == 0) {
                // System.out.println("First player: " + start1 + " " + end1);
                if(i < n - 1 && chars1.get(start1) > chars2.get(end2)) {
                    result[resultEnd] = chars1.get(end1);
                    end1--;
                    resultEnd--;
                }
                else {
                    result[resultStart] = chars1.get(start1);
                    start1++;
                    resultStart++;
                }
            }
            else if(i % 2 == 1) {
                // System.out.println("Second player: " + start2 + " " + end2);
                if(i < n - 1 && chars2.get(end2) < chars1.get(start1)) {
                    result[resultEnd] = chars2.get(start2);
                    start2++;
                    resultEnd--;
                }
                else {
                    result[resultStart] = chars2.get(end2);
                    end2--;
                    resultStart++;
                }
            }
        }

        StringBuilder resultStr = new StringBuilder();
        for(int i = 0; i < n; i++) {
            resultStr.append(result[i]);
        }
        System.out.println(resultStr.toString());
    }
}
