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.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.util.Deque;
import java.util.ArrayDeque;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author P Marecki
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(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, InputReader in, PrintWriter out) {
            char[] oo = in.next().toCharArray();
            char[] aa = in.next().toCharArray();
            int n = oo.length;
            Arrays.sort(oo);
            Arrays.sort(aa);
            Deque<Character> O = new ArrayDeque<>();
            Deque<Character> A = new ArrayDeque<>();
            for (int i = 0; i < (n + 1) / 2; i++) O.addLast(oo[i]);
            for (int i = 0; i < n / 2; i++) A.addLast(aa[aa.length - 1 - i]); //po lewej duze

            char[] a = new char[n];
            int nn = n;
            int t = 0;
            int L = 0, R = n - 1;
            while (n-- > 0) {
                if (t % 2 == 0) {
                    if (A.size() == 0 || O.peekFirst() < A.peekFirst()) {
                        a[L++] = O.pollFirst();
                    } else {
                        a[R--] = O.pollLast();
                    }
                } else {
                    if (O.size() == 0 || A.peekFirst() > O.peekFirst()) {
                        a[L++] = A.pollFirst();
                    } else {
                        a[R--] = A.pollLast();
                    }
                }
                t ^= 1;
            }
            out.println(new String(a));

        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

    }
}

