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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.DecimalFormat;
import java.util.*;

public class Main2 {

    static long mod = 1000000007L;

    public static void main(String[] args) throws Exception {
        FastScanner scanner = new FastScanner();
        char[] olega = scanner.nextLine().toCharArray();
        char[] igora = scanner.nextLine().toCharArray();
        int n = olega.length;

        Arrays.sort(olega);
        Arrays.sort(igora);
        char[] igorn = new char[igora.length];
        for (int i = 0; i < igora.length; i++) {
            igorn[i] = igora[igora.length - 1 - i];
        }
        olega = Arrays.copyOf(olega, n / 2 + (n % 2 == 0 ? 0 : 1));
        igorn = Arrays.copyOf(igorn, n / 2);
        char[] olegn = reverse(olega);
        igora = reverse(igorn);

        int i = 0;
        int oli = 0;
        int igi = 0;
        char[] res = new char[n];
        while (i < n) {
            if (oli < olega.length && igi < igorn.length && olega[oli] >= igorn[igi]) {
                break;
            }
            if (i % 2 == 0) res[i] = olega[oli++]; else res[i] = igorn[igi++];
            i++;
        }

        oli = 0;
        igi = 0;
        int finish = i;
        for (int j = n - 1; j >= finish; j--) {
            if (i % 2 == 0) res[j] = olegn[oli++]; else res[j] = igora[igi++];
            i++;
        }
        System.out.println(String.valueOf(res));

    }

    static char[] reverse(char[] a) {
        char[] r = new char[a.length];
        for (int i = 0; i < a.length; i++) r[i] = a[a.length - 1 - i];
        return r;
    }

    public static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String nextToken() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        String nextLine() {
            try {
                return br.readLine();
            } catch (Exception e) {
                e.printStackTrace();
                throw new RuntimeException();
            }
        }

        int nextInt() {
            return Integer.parseInt(nextToken());
        }

        long nextLong() {
            return Long.parseLong(nextToken());
        }

        double nextDouble() {
            return Double.parseDouble(nextToken());
        }
    }
}
