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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.*;
import java.util.Collections;
import java.util.PriorityQueue;
import java.util.StringTokenizer;

public class CFA {
    public static PrintWriter out;
    public static FastScanner in;

    private void solve() {
        String oleg = in.nextLine();
        String igor = in.nextLine();

        PriorityQueue<Character> og = new PriorityQueue<>();
        PriorityQueue<Character> ir = new PriorityQueue<>(Collections.reverseOrder());

        int n = oleg.length();
        for(int i=0;i<n;i++){
            og.add(oleg.charAt(i));
        }

        for(int i=0;i<n;i++){
            ir.add(igor.charAt(i));
        }

        for(int i=0;i<n;i++){
            if(i%2 == 0) out.print(og.poll());
            else out.print(ir.poll());
        }
        out.println();
    }

    private void runIO() {
        in = new FastScanner();
        out = new PrintWriter(new BufferedOutputStream(System.out));
        solve();
        out.close();
    }

    private static class FastScanner {
        BufferedReader bufferedReader;
        StringTokenizer stringTokenizer;

        private FastScanner() {
            bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        }

        private String next() {
            if (stringTokenizer == null || !stringTokenizer.hasMoreElements()) {
                try {
                    stringTokenizer = new StringTokenizer(bufferedReader.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return stringTokenizer.nextToken();
        }

        private int nextInt() {
            return Integer.parseInt(next());
        }

        private long nextLong() {
            return Long.parseLong(next());
        }

        private String nextLine() {
            String ret = "";
            try {
                ret = bufferedReader.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return ret;
        }
    }

    public static void main(String[] args) {
        new CFA().runIO();
    }
}
