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

bccdb
 z
 dfdeed
 aab
 y
 abac

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

public class namingcompany {

    static char[] o,ig,a,b;
    static boolean[] filled;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        o = br.readLine().toCharArray();
        ig = br.readLine().toCharArray();
        int len=o.length;
        int k=(len+1)/2;
        a = new char[(len+1)/2];
        b=new char[(len)/2];
        Arrays.sort(o);
        Arrays.sort(ig);
        for (int i = 0; i <b.length ; i++) {
            a[i]=o[i];
            b[i]=ig[len-1-i];
        }
        a[a.length-1]=o[a.length-1];

        filled=new boolean[len];
        char r[] = new char[o.length];
        int lefto=0, righto=a.length-1, lefti=0, righti=b.length-1,leftr=0,rightr=len-1;

        for (int i = 0; i < len; i++) {
            if (i % 2 == 0) {
                if ((rightr < 0) || (rightr < leftr) || (lefto < k && lefti<b.length && a[lefto] < b[lefti])) {//min(a)<max(b) fill left with min(a)
                    r[leftr++] = a[lefto++];
                } else { //min(a)>=max(b), use max(a) fill right;
                    r[rightr--] = a[righto--];
                }
            } else {//==1
                if ((rightr < 0) || (rightr < leftr) || (lefto > k - 1 || b[lefti] > a[lefto])) {//max(b)>min(a) fill left with max(b)
                    r[leftr++] = b[lefti++];
                } else {//max(b)<=min(a), use min(b) to fill right.
                    r[rightr--] = b[righti--];
                }
            }
        }
        System.out.println(new String(r));
    }

    public static int upper_bound(char[] arr, int key) {
        int len = arr.length;
        int lo = 0;
        int hi = len - 1;
        int mid = (lo + hi) / 2;
        while (lo < hi) {
            if (arr[mid] > key) {
                hi = mid;
            } else {
                lo = mid + 1;
            }
            mid = (lo + hi) / 2;
        }
        return lo;
    }
}
/*
reddit
abcdef

dfdeed

cbxz
aaaa

abac

bcdef
abbbc

bccdb
 */