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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;
import java.util.Collections;
import java.util.ArrayList;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        public void solve(int testNumber, Scanner in, PrintWriter out) {

            char[] s = in.nextLine().toCharArray();
            char[] t = in.nextLine().toCharArray();

            Arrays.sort(s);
            Arrays.sort(t);

            ArrayList<Character> queueS = new ArrayList<>();
            ArrayList<Character> queueT = new ArrayList<>();

            int cnts = (int) Math.ceil((double) s.length / 2.0);
            int cntt = (int) Math.floor((double) s.length / 2.0);


            for (int i = 0; i < cnts; ++i)
                queueS.add(s[i]);

            int index = t.length;
            while (queueT.size() < cntt) {
                queueT.add(t[--index]);
            }


            Collections.sort(queueS);
            Collections.sort(queueT, Collections.reverseOrder());

            char[] rst = new char[s.length];
            int head = 0, tail = s.length - 1;
            for (int i = 0; i < s.length; ++i) {
                if (i % 2 == 0) {
                    if (queueT.isEmpty()) {

                        rst[tail--] = queueS.get(0);
                        queueS.remove(0);
                    } else if (queueS.get(queueS.size() - 1) <= queueT.get(0)) {
                        rst[head++] = queueS.get(0);
                        queueS.remove(0);
                    } else {
                        rst[tail--] = queueS.get(queueS.size() - 1);
                        queueS.remove(queueS.size() - 1);
                    }
                } else {
                    if (queueS.isEmpty()) {
                        rst[head++] = queueT.get(0);
                        queueT.remove(0);
                    } else if (queueT.get(0) >= queueS.get(queueS.size() - 1)) {
                        rst[head++] = queueT.get(0);
                        queueT.remove(0);
                    } else {
                        rst[tail--] = queueT.get(queueT.size() - 1);
                        queueT.remove(queueT.size() - 1);
                    }
                }
            }

            for (int i = 0; i < s.length; ++i)
                out.printf("%s", rst[i]);
        }

    }
}

