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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.util.*;
public class NamingCompany {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		char oleg[] = in.next().toCharArray(), igor[] = in.next().toCharArray();
		int Oplace = 0, Iplace = igor.length - 1;
		String result = "";
		Arrays.sort(oleg);
		Arrays.sort(igor);
		for (int i = 0; i < oleg.length; i++){
			if (i % 2 == 0){
				result += oleg[Oplace];
				Oplace++;
			} else if (i % 2 != 0){
				result += igor[Iplace];
				Iplace--;
			}
		}
		System.out.println((result.charAt(0) > result.charAt(result.length() - 1)) ? new StringBuilder(result).reverse().toString() : result );
		
	}

}
