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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.util.*;

/**
 * Created by vrajegowda on 6/6/17.
 */
public class NamingComapany {
    public static void main(String[] args){
        String oleg;
        String igor;
        Scanner sc = new Scanner(System.in);
        oleg= sc.next();
        igor=sc.next();
        char [] arr1=oleg.toCharArray();
        char [] arr2=igor.toCharArray();
        Arrays.sort(arr1);
        Arrays.sort(arr2);

        char [] res= new char[arr1.length];
        int k=0;
        int l=arr1.length-1;
        boolean f=false;
        int i=0,ie=(arr1.length-1)/2;
        int j=arr2.length-1 , je=(int)(Math.ceil(arr2.length)/2.0);
        //int l=arr2.length-1;
        while(k<arr1.length ){
           // k++;
            if(!f ) {
                if (arr1[i] >= arr2[j]) {
                    res[l] = arr1[ie];
                    ie--;
                    l--;
                    f = true;
                }
                else{
                    res[k]=arr1[i];
                    i++;
                   // k++;
                    f=true;
                }
            }
            else{
                if(arr1[i] >= arr2[j]){
                    res[l]=arr2[je];
                    je++;
                    l--;
                }
                else {
                    res[k]=arr2[j];
                   // k++;
                    j--;
                }
                f=false;
            }
            k++;


        }
        System.out.println(String.valueOf(res));
    }
}