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 {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        char[] olegChars = scanner.nextLine().toCharArray();
        char[] igorChars = scanner.nextLine().toCharArray();
        char[] finalString = new char[olegChars.length];
        int n = olegChars.length;
        int olegBeginPosition = 0;
        int igorBeginPosition =  n - (n / 2);;
        int finalStringPos = 0;

        Arrays.sort(olegChars);
        Arrays.sort(igorChars);

        int olegEndPosition = (n / 2) + (n % 2) - 1;
        int igorEndPosition = igorChars.length - 1;
        int lastElemPos = n - 1;
        int turn = 1;
        for (int i = 0; i < n; i++) {
            if (turn == 1) {
                if (olegChars[olegBeginPosition] < igorChars[igorEndPosition]) {
                    finalString[finalStringPos++] = olegChars[olegBeginPosition++];
                } else {
                    finalString[lastElemPos--] = olegChars[olegEndPosition--];
                }
            } else {
                if (igorChars[igorEndPosition] > olegChars[olegBeginPosition]) {
                    finalString[finalStringPos++] = igorChars[igorEndPosition--];
                } else {
                    finalString[lastElemPos--] = igorChars[igorBeginPosition++];
                }
            }
            turn *= -1;
        }
        System.out.println(String.valueOf(finalString));
    }
}


