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

bccdb
 z
 dfdeed
 aab
 y
 abac


import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

 

public class name
{
    public static void main(String args[])
    {
        Scanner sc=new Scanner(System.in);
        
        String s=sc.next();
        String s2=sc.next();
        
        Integer ol[]=new Integer[s.length()];
        Integer ad[]=new Integer[s2.length()];
        
        char res[]=new char[s.length()];
        
        for(int i=0;i<s.length();i++)
        {
            ol[i]=(int)s.charAt(i);
            ad[i]=(int)s2.charAt(i);
            
        }
        
        java.util.Arrays.sort(ol);
        java.util.Arrays.sort(ad,Collections.reverseOrder());
        
        int n=s.length();
       
        
        int rl=0; int rr=n-1; 
        
        int count=0;
        
        int lower=n/2;
        int upper=n-lower;
        
        int left=0,right=upper-1;
        int left2=0,right2=lower-1;
        
        
        for(int i=0;i<s.length();i++)
        {
            if(i%2==0)
            {
                if(ol[left]<ad[left2] && left<upper)
                {
                    res[rl]=(char)(int)ol[left];
                    left++;
                    rl++;
                    
                }
                else if(right>=0)
                {
                    res[rr]=(char)(int)ol[right];
                    right--;
                    rr--;
                    
                }
            count++;
            }
            else
            {
                if(ad[left2]>ol[left] && left2<lower)
                {
                    res[rl]=(char)(int)ad[left2];
                    rl++;
                    left2++;
                }
                else if(right2>=0)
                {
                
                    res[rr]=(char)(int)ad[right2];
                    right2--;
                    rr--;
                }
                count++;
            }
            if(count>=n)
                break;
        
        }
        
        for(int i=0;i<n;i++)
            System.out.print(res[i]);
        
    
    }

}


