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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;
import java.util.Scanner;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;

public class main {
	private static InputStream stream;
	private static byte[] buf = new byte[1024];
	private static int curChar;
	private static int numChars;
	private static SpaceCharFilter filter;
	private static PrintWriter pw;
	private static long mod = 1000000000 + 7;
	private static int MAX=1000001;
	private static int block;
	private static void soln(){
		char[] arr1=nextLine().toCharArray();
		char[] arr2=nextLine().toCharArray();
		int[] sort=new int[26];
		for(int i=0;i<arr1.length;i++)
			sort[arr1[i]-'a']++;
		int j=0;
		for(int i=0;i<26;i++){
			while(sort[i]-->0){
				arr1[j++]=(char) ('a'+i);
				//pw.println(arr1[j-1]);
			}
		}
		for(int i=0;i<26;i++)
			sort[i]=0;
		for(int i=0;i<arr2.length;i++)
			sort[arr2[i]-'a']++;
		j=0;
		for(int i=25;i>=0;i--){
			while(sort[i]-->0){
				arr2[j++]=(char) ('a'+i);
				//pw.println(arr2[j-1]);
			}
		}
		boolean f=true;
		boolean another=false;
		int last=arr1.length-1;
		int l1=(arr1.length+1)/2-1;
		int l2=arr1.length/2-1;
		char[] arr=new char[arr1.length];
		int a1=0;
		int a2=0;
		int first=0;
		for(int i=0;i<arr1.length;i++)
			if(f){
				if(another){
					arr[last--]=arr1[l1--];
				}else{
					if(arr1[a1]>=arr2[a2]){
						another=true;
						arr[last--]=arr1[l1--];
					}else
						arr[first++]=arr1[a1++];
				}
				f=false;
			}else{
				if(another){
					arr[last--]=arr2[l2--];
				}else{
					if(arr1[a1]>=arr2[a2]){
						another=true;
						arr[last--]=arr2[l2--];
					}else
						arr[first++]=arr2[a2++];
				}
				f=true;
			}
			for(int i=0;i<arr.length;i++)
				pw.print(arr[i]);
		}
	static class Pair implements Comparable<Pair>{
		int p;
		int c;
		int b;
		public Pair(int t,int x,int y){
			p=t;
			c=x;
			b=y;
		}
		@Override
		public int compareTo(Pair arg0) {
			return this.p-arg0.p;
		}
		
	}
	private static class DSU{
		int[] parent;
		public DSU(int n){
			parent=new int[n];
			for(int i=0;i<n;i++)
				parent[i]=i;
		}
		int find(int i){
	        while(parent[i] !=i){
	        	parent[i]=parent[parent[i]];
	        	i=parent[i];
	        }
	        return i;
	    }
		void Union(int x, int y){
	        int xset = find(x);
	        int yset = find(y);
	        parent[yset]=yset;
	        parent[xset] = yset;
	    }
	}
	private static class Edge{
		int x;
		int y;
		int i;
		public Edge(int a,int b,int c){
			x=a; y=b;i=c;
		}
	}
	private static long pow(long a, long b, long c) {
		if (b == 0)
			return 1;
		long p = pow(a, b / 2, c);
		p = (p * p) % c;
		return (b % 2 == 0) ? p : (a * p) % c;
	}
	
	private static class Mo implements Comparable<Mo>{
		int l;
		int r;
		int i;
		public Mo(int a,int b,int ind) {
			l=a;r=b;i=ind;
		}
		@Override
		public int compareTo(Mo arg0) {
			int b1=this.l/block;
			int b2=arg0.l/block;
			return (b1!=b2)?(b1-b2):(this.r-arg0.r);
		}
	}

	private static long gcd(long n, long l) {
		if (l == 0)
			return n;
		return gcd(l, n % l);
	}

	private static long max(long a, long b) {
		if (a > b)
			return a;
		return b;
	}

	private static long min(long a, long b) {
		if (a < b)
			return a;
		return b;
	}

	public static void main(String[] args) throws Exception {
		new Thread(null,new Runnable(){
			@Override
			public void run() {
				/*try {
					InputReader(new FileInputStream("C:\\Users\\hardik\\Desktop\\C-small-1-attempt1.in"));
				} catch (FileNotFoundException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}*/
				InputReader(System.in);
				pw = new PrintWriter(System.out);
				/*try {
					pw=new PrintWriter(new FileOutputStream("C:\\Users\\hardik\\Desktop\\out.txt"));
				} catch (FileNotFoundException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}*/
				soln();
				pw.close();
			}
		},"1",1<<26).start();
	}

	public static void InputReader(InputStream stream1) {
		stream = stream1;
	}

	private static boolean isWhitespace(int c) {
		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	private static boolean isEndOfLine(int c) {
		return c == '\n' || c == '\r' || c == -1;
	}

	private static int read() {
		if (numChars == -1)
			throw new InputMismatchException();
		if (curChar >= numChars) {
			curChar = 0;
			try {
				numChars = stream.read(buf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (numChars <= 0)
				return -1;
		}
		return buf[curChar++];
	}

	private static int nextInt() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		int res = 0;
		do {
			if (c < '0' || c > '9')
				throw new InputMismatchException();
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	private static long nextLong() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		long res = 0;
		do {
			if (c < '0' || c > '9')
				throw new InputMismatchException();
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	private static String nextToken() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		StringBuilder res = new StringBuilder();
		do {
			res.appendCodePoint(c);
			c = read();
		} while (!isSpaceChar(c));
		return res.toString();
	}

	private static String nextLine() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		StringBuilder res = new StringBuilder();
		do {
			res.appendCodePoint(c);
			c = read();
		} while (!isEndOfLine(c));
		return res.toString();
	}

	private static int[] nextIntArray(int n) {
		int[] arr = new int[n];
		for (int i = 0; i < n; i++) {
			arr[i] = nextInt();
		}
		return arr;
	}

	private static long[] nextLongArray(int n) {
		long[] arr = new long[n];
		for (int i = 0; i < n; i++) {
			arr[i] = nextLong();
		}
		return arr;
	}

	private static void pArray(int[] arr) {
		for (int i = 0; i < arr.length; i++) {
			System.out.print(arr[i] + " ");
		}
		System.out.println();
		return;
	}

	private static void pArray(long[] arr) {
		for (int i = 0; i < arr.length; i++) {
			System.out.print(arr[i] + " ");
		}
		System.out.println();
		return;
	}

	private static boolean isSpaceChar(int c) {
		if (filter != null)
			return filter.isSpaceChar(c);
		return isWhitespace(c);
	}
	private static char nextChar() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		char c1=(char)c;
		while(!isSpaceChar(c))
			c=read();
		return c1;
}
	private interface SpaceCharFilter {
		public boolean isSpaceChar(int ch);
	}
}