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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.*;
import java.util.*;

public class A {
    public static void main(String[] args) throws Exception {
        FastScanner fs = new FastScanner();
Scanner s = new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);

        char[] a = s.nextLine().toCharArray();
        char[] b = s.nextLine().toCharArray();
        Arrays.sort(a);
        Arrays.sort(b);
        int p1 = 0, p2 = b.length-1;
        StringBuilder res = new StringBuilder();
        for(int i = 0; i < a.length; i++) {
            if(i%2==0) {
                res.append(a[p1++]);
            } else {
                res.append(b[p2--]);
            }
        }
        out.println(res.toString());

        out.close();
    }


    static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner() {
            try	{
                br = new BufferedReader(new InputStreamReader(System.in));
//                br = new BufferedReader(new FileReader("testdata.out"));
                st = new StringTokenizer("");
            } catch (Exception e){e.printStackTrace();}
        }

        public String next() {
            if (st.hasMoreTokens())	return st.nextToken();
            try {st = new StringTokenizer(br.readLine());}
            catch (Exception e) {e.printStackTrace();}
            return st.nextToken();
        }

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

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

        public double nextDouble() {return Double.parseDouble(next());}

        public String nextLine() {
            String line = "";
            try {line = br.readLine();}
            catch (Exception e) {e.printStackTrace();}
            return line;
        }

        public Integer[] nextIntegerArray(int n) {
            Integer[] a = new Integer[n];
            for(int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        public int[] nextIntArray(int n) {
            int[] a = new int[n];
            for(int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        public char[] nextCharArray() {
            return nextLine().toCharArray();
        }
    }
}

