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

bccdb
 z
 dfdeed
 aab
 y
 abac


import java.util.*;
import java.io.*;
import java.math.BigInteger;

public class TestClass {

	static PrintWriter out = new PrintWriter(System.out);
	public static void main(String[] args) throws Exception{
		
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String x = in.readLine();
		String y = in.readLine();
		int n = x.length();
		char a[] = x.toCharArray();
		char b[] = y.toCharArray();
		Arrays.sort(a);
		Arrays.sort(b);
		int i1=0,j1=(n-1)/2,i2=(int)Math.ceil(n/2.0),j2=n-1;
		char ans[] = new char[n];
		int p=0,q=n-1,f=0,k=0;
//		for(int i=0;i<n;i++)
//		{
//			out.print(b[i]);
//		}
		while(k<n)
		{
			if(f==0)
			{
				if(a[i1]>=b[j2])
				{
					ans[q] = a[j1];
					j1--;
					q--;
				}
				else
				{
					ans[p] = a[i1];
					i1++;
					p++;
				}
				f=1;
			}
			else
			{
				if(a[i1]>b[j2])
				{
					ans[q] = b[i2];
					i2++;
					q--;
				}
				else
				{
					ans[p] = b[j2];
					j2--;
					p++;
				}
				f=0;
			}
			k++;
//			for(int o=0;o<n;o++)
//			{
//				if(ans[o]==' ')
//				{
//					out.println(o+" "+' ');
//				}
//				else
//				{
//					out.println(o+" "+ans[o]);
//				}
//			}
//			out.println();
		}
		for(int i=0;i<n;i++)
		{
			out.print(ans[i]);
		}
		out.close();
	}
	
}	
