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

bccdb
 z
 dfdeed
 aab
 y
 abac

/**
 * Created by Ariana Herbst on 5/13/17.
 */

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

/**
 * Created by Ariana Herbst on 5/13/17
 */
public class cfs414C {

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        StringBuilder sb = new StringBuilder();
        char[] A = sc.next().toCharArray();
        char[] B = sc.next().toCharArray();
        Arrays.sort(A);
        Arrays.sort(B);
        StringBuilder sb1 = new StringBuilder();
        StringBuilder sb2 = new StringBuilder();
        for (int i = 0; i < A.length; i++) {
            sb1.append(A[i]);
            sb2.append(B[i]);
        }
        sb2.reverse();
        sb1 = new StringBuilder(sb1.substring(0, A.length / 2 + A.length % 2));
        sb2 = new StringBuilder(sb2.substring(0, A.length / 2));
        sb1.reverse();
        sb2.reverse();
        int b = 0;
        int a = 0;
        //char[] ans = new char[A.length];
        StringBuilder ans = new StringBuilder();
        //int front = 0;
        //int back = A.length-1;
        for (int i = 0; i < A.length; i++) {
            if ((i&1) == 1) { /// lexographically last
                if (sb2.charAt(b) < sb.charAt(0)) {
                    sb.insert(0, sb2.charAt(b++));
                    //ans[front++] = B[b--];
                } else {
                    sb.append(sb2.charAt(b++));
                    //ans[back--] = B[b--];
                }
                //sb.append(B[b--]);
            } else {    /// lexographically first
                if (sb.length() == 0 || sb1.charAt(a) > sb.charAt(0)) {
                    sb.insert(0, sb1.charAt(a++));
                   // ans[front++] = A[a++];
                } else {
                    sb.append(sb1.charAt(a++));
                    //ans[back--] = A[a++];
                }
                //sb.append(A[a++]);
            }
           // sb.reverse();
         //   System.out.println(sb.toString());
        }

        sb.reverse();

        System.out.println(sb);
    }


    public static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner(Reader in) {
            br = new BufferedReader(in);
        }

        public FastScanner() {
            this(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

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

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

        String readNextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        int[] readIntArray(int n) {
            int[] a = new int[n];
            for (int idx = 0; idx < n; idx++) {
                a[idx] = nextInt();
            }
            return a;
        }

        long[] readLongArray(int n) {
            long[] a = new long[n];
            for (int idx = 0; idx < n; idx++) {
                a[idx] = nextLong();
            }
            return a;
        }
    }
}
