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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.util.*;
import java.io.*;
 
public class Main{
    static BufferedReader br = 
            new BufferedReader(new InputStreamReader(System.in));
    static BufferedWriter bw = 
            new BufferedWriter(new OutputStreamWriter(System.out));
    static StringTokenizer st;
    
    public static void main(String args[]) throws IOException{
        Scanner sc = new Scanner(System.in);
        char[] A, B, C;
        int L, i, l, r;
        A = br.readLine().toCharArray();
        B = br.readLine().toCharArray();
        L = A.length;
        Arrays.sort(A);
        Arrays.sort(B);
        Deque<Character> dqA = new ArrayDeque<Character>();
        Deque<Character> dqB = new ArrayDeque<Character>();
        for(i = 0; i < (L+1)/2; i++) dqA.push(A[i]);
        for(i = 0; i < L/2; i++) dqB.push(B[L-1-i]);
        C = new char[L];
        l = 0;
        r = L-1;
        for(i = 0; i < L; i++){
        	if(i == L-1){
        		C[l] = (L%2 == 1) ? dqA.pollFirst() : dqB.pollFirst();
        		break;
        	}
        	if(i%2 == 0){
        		if(dqA.peekLast() >= dqB.peekLast()) C[r--] = dqA.pollFirst();
        		else C[l++] = dqA.pollLast();
        	}else{
        		if(dqA.peekLast() >= dqB.peekLast()) C[r--] = dqB.pollFirst();
        		else C[l++] = dqB.pollLast();
        	}
        }
        for(i = 0; i < L; i++) bw.write(C[i]+"");
        bw.close();
    }
}