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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.StringTokenizer;

/**
 * Created by vitalii on 13.02.2016.
 */
public class C {

    void solveOleg(char[] a, char[] b, int p1, int p2, int left, int sign)
    {
        if (left == 0)
        {
            return;
        }
        if (a[p1]*sign < b[p2]*sign)
        {
            out.print(a[p1]);
            solveOleg(b,a,p2,p1+1,left-1,-sign);
            return;
        }


        for (int i = 0; i < left; i++)
        {
            if (i%2 != left %2)
            {
                out.print(a[p1]);
                p1++;
            }
            else
            {
                out.print(b[p2]);
                p2++;
            }
        }
    }

    public void solve() throws IOException {
        char[] a = next().toCharArray();
        char[] b = next().toCharArray();

        Arrays.sort(a);
        Arrays.sort(b);

        for (int i = 0; i < b.length -i - 1; i++)
        {
            char t = b[i];
            b[i] = b[b.length-i-1];
            b[b.length-i-1] = t;
        }

        solveOleg(a,b,0,0,a.length, 1);

        out.println();
    }


    public static void main(String[] args) throws IOException {
        new C().run();
    }

    public void run() throws IOException {
        in = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
        solve();
        out.close();
    }

    BufferedReader in;
    PrintWriter out;
    StringTokenizer st;

    public String next() throws IOException {
        while (st == null || !st.hasMoreElements()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }

    public Long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    public Integer nextInt() throws IOException {
        return Integer.parseInt(next());
    }


}