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.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.StringTokenizer;

public class C {
    public static void main(String[] args) throws IOException {
        InputScanner is = new InputScanner();

        String s1 = is.next();
        String s2 = is.next();

        int n = s1.length();

        Character[] oleg = s1.chars().mapToObj(c -> (char)c).toArray(Character[]::new);
        Character[] igor = s2.chars().mapToObj(c -> (char)c).toArray(Character[]::new);

        Arrays.sort(oleg);
        Arrays.sort(igor, Collections.reverseOrder());

        StringBuilder ans = new StringBuilder();

        char[] name = new char[n];

        int start = 0;
        int end = n-1;

        boolean olegMove = true;
        int olegIndex = 0;
        int igorIndex = 0;

        int olegMoves = (n%2==0) ? n/2 : n/2 +1;
        int igorMoves = n/2;

        while (start <= end) {
            if (olegMove){
                olegMove = false;
                if (oleg[olegIndex] >= igor[igorIndex]){
                    name[end] = oleg[olegIndex+olegMoves-1];
                    end--;
                }else{
                    name[start] = oleg[olegIndex];
                    start++;
                    olegIndex++;
                }
                olegMoves--;
            }else{
                olegMove = true;
                if (igor[igorIndex] <= oleg[olegIndex]){
                    name[end] = igor[igorIndex + igorMoves-1];
                    end--;
                }else{
                    name[start] = igor[igorIndex];
                    start++;
                    igorIndex++;
                }
                igorMoves--;
            }
        }

        System.out.println(new String(name));
    }



    static class InputScanner {
        BufferedReader br;
        StringTokenizer st;

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

        public String next() throws IOException {
            if (st == null || !st.hasMoreTokens()) {
                String line = br.readLine();
                st = new StringTokenizer(line);
            }
            return st.nextToken();
        }

        public int nextInt() throws IOException {
            String next = next();
            return Integer.parseInt(next);
        }

        public long nextLong() throws IOException {
            String next = next();
            return Long.parseLong(next);
        }
    }
}

