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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.lang.*;
import java.io.*;
import java.util.*;

public class MyClass {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.println(nameCompany(sc.nextLine(), sc.nextLine()));
	}

	public static String nameCompany(String a, String b) {
		char[] low = a.toCharArray();
		Arrays.sort(low);
		char[] high = b.toCharArray();
		Arrays.sort(high);

		int lowLeft = 0;
		int lowRight = (low.length + 1)/2 - 1;
		int highLeft = lowRight + 1;
		int highRight = low.length - 1;
		int currentLeft = 0;
		int currentRight = low.length - 1;

		boolean pickLow = true;

		char[] res = new char[low.length];

		for (int i = 0; i < res.length; i++) {
			if (pickLow) {
				if (low[lowLeft] < high[highRight]) {
					// Fill from left.
					res[currentLeft] = low[lowLeft];
					lowLeft++;
					currentLeft++;
				} else {
					// Fill from right.
					res[currentRight] = low[lowRight];
					lowRight--;
					currentRight--;
				}
			} else {
				if (low[lowLeft] < high[highRight]) {
					// Fill from left.
					res[currentLeft] = high[highRight];
					highRight--;
					currentLeft++;
				} else {
					// Fill from right.
					res[currentRight] = high[highLeft];
					highLeft++;
					currentRight--;

				}
			}
			pickLow = !pickLow;
		} 

		return String.valueOf(res);	
	}
}









