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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.util.Arrays;
import java.util.Scanner;

public class Main {
	
	static char[] first = new char[300010];
	static char[] second = new char[300010];
	
	public static void main(String[] args) {
		
		Scanner in = new Scanner(System.in);
		while (in.hasNext()) {
			first = in.next().toCharArray();
			second = in.next().toCharArray();
			//��0��first.length������������򣬰���0������first.length
			Arrays.sort(first,0,first.length);
			Arrays.sort(second,0,second.length);
			String str = "";
			int len = first.length;
			int i;
			for (i=0; i<len/2; i++) {
				str += first[i];
				str += second[len-1-i];
			}
			if ((len & 1) == 1)
				str += first[i];
			System.out.println(str);
		}
	}

}
