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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.util.*;

// Oleg wants the company name to be as lexicographically small as possible 
// while Igor wants the company name to be as lexicographically large as possible.
public class Round414C_Naming_Company
{
	public static void main(String args[])
	{
		Scanner in = new Scanner(System.in);
		char Oleg[] = in.next().toCharArray(), Igor[] = in.next().toCharArray();
		
		Arrays.sort(Oleg);
		Arrays.sort(Igor);
		
		char result[] = new char[Oleg.length];
		int Oleg_start = 0, Oleg_end = (Oleg.length - 1) / 2;
		int Igor_start = (Oleg.length % 2 == 0) ? Oleg.length/2 : Oleg.length / 2 + 1, Igor_end = Oleg.length - 1;
		int index = result.length - 1;
		
		for (int i = 0; i < Oleg.length; i++)
		{
			if (i % 2 == 0)
			{
				if (Oleg[Oleg_start] >= Igor[Igor_end])
				{
					result[index] = Oleg[Oleg_end];
					Oleg_end--;
					index--;
				}
				else
				{
					result[i] = Oleg[Oleg_start];
					Oleg_start++;
				}
				
			}
			else
			{
				if (Oleg[Oleg_start] >= Igor[Igor_end])
				{
					result[index] = Igor[Igor_start];
					Igor_start++;
					index--;
				}
				else
				{
					result[i] = Igor[Igor_end];
					Igor_end--;
				}
				
			}
		}
		
		for (int i = 0; i < result.length; i++)
			System.out.print(result[i]);
	}
}
