Problem:
Score : 800 points

Problem Statement

You are given integers N,\ A and B.
Determine if there exists a permutation (P_0,\ P_1,\ ...\ P_{2^N-1}) of (0,\ 1,\ ...\ 2^N-1) that satisfies all of the following conditions, and create one such permutation if it exists.

P_0=A

P_{2^N-1}=B

For all 0 \leq i < 2^N-1, the binary representations of P_i and P_{i+1} differ by exactly one bit.

Constraints

1 \leq N \leq 17

0 \leq A \leq 2^N-1

0 \leq B \leq 2^N-1

A \neq B

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N A B

Output

If there is no permutation that satisfies the conditions, print NO.

If there is such a permutation, print YES in the first line.
Then, print (P_0,\ P_1,\ ...\ P_{2^N-1}) in the second line, with spaces in between.
If there are multiple solutions, any of them is accepted.

Sample Input 1

2 1 3

Sample Output 1

YES
1 0 2 3

The binary representation of P=(1,0,2,3) is (01,00,10,11), where any two adjacent elements differ by exactly one bit.

Sample Input 2

3 2 1

Sample Output 2

NO

Solution in Java7 (OpenJDK 1.7.0) (judge verdict: Wrong Answer)

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

	static BufferedReader reader;
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		reader = new BufferedReader(new InputStreamReader(System.in));
		String[] s = readLine().split(" ");
		int N = Integer.parseInt(s[0]);
		int A = Integer.parseInt(s[1]);
		int B = Integer.parseInt(s[2]);
		boolean[] A_b = new boolean[N];
		boolean[] B_b = new boolean[N];
		int diff_cnt = 0;
		for(int i=0;i<N;i++){
			A_b[i] = ((A&bit(N-i-1))!=0);
			B_b[i] = ((B&bit(N-i-1))!=0);
			if(A_b[i]!=B_b[i]){diff_cnt++;}
		}
		if(diff_cnt%2==0){print("NO");}
		else{
			StringBuilder sb = new StringBuilder("YES\n");
			for(int k=0;k<bit(N);k++){
				int out = 0;
				for(int i=0;i<N;i++){
					out=out*2+(A_b[i]?1:0);
				}
				sb.append(out).append(" ");
				int change_pointer = 0;
				boolean changed = false;
				for(int i=change_pointer+1;i<N;i++){
					if(A_b[i]!=B_b[i]){
						A_b[i]=B_b[i];
						changed = true;
						change_pointer = i;
						break;
					}
				}
				if(!changed){
					A_b[0]=!A_b[0];
				}
			}
			print(sb.toString().trim());
		}
	}
	
	private static int bit(int d){
		if(d<=0){return 1;}
		return bit(d-1)*2;
	}

	private static String readLine(){
		try{
			return reader.readLine();
		}catch(Exception e){
			return e.getMessage();
		}
	}
	private static void print(Object o){
		System.out.println(o);
	}
	private static void print(){
		System.out.println();
	}
}