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.io.InputStreamReader;
import java.io.InputStream;

/**
 * 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;
        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) {
            String s = in.next();
            String t = in.next();
            Character[] sArr = new Character[s.length()];
            Character[] tArr = new Character[t.length()];
            for (int i = 0; i < sArr.length; i++) {
                sArr[i] = s.charAt(i);
                tArr[i] = t.charAt(i);
            }
            Arrays.sort(sArr);
            Arrays.sort(tArr, (Character fi, Character se) -> se - fi);
            char[] ans = new char[sArr.length];
            for (int i = 0, j = 0; i < ans.length; i += 2, j++) {
                ans[i] = sArr[j];
            }
            for (int i = 1, j = 0; i < ans.length; i += 2, j++) {
                ans[i] = tArr[j];
            }
            out.println(ans);
        }

    }

    static class InputReader {
        private BufferedReader reader;
        private StringTokenizer stt;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream));
        }

        public String nextLine() {
            try {
                return reader.readLine();
            } catch (IOException e) {
                return null;
            }
        }

        public String next() {
            while (stt == null || !stt.hasMoreTokens()) {
                stt = new StringTokenizer(nextLine());
            }
            return stt.nextToken();
        }

    }
}

