99
1
3
2
2
3
1
1
3
3
3
3
3
3
1
1
3
3
3
3
1
1
3
2
1
1
1
1
1
1
1
3
2
2
2
1
3
3
1
1
3
2
1
3
3
1
2
3
3
3
1
2
2
2
3
3
3
3
3
3
2
2
2
2
3
3
3
1
1
3
2
1
1
2
2
2
3
3
2
1
1
2
2
1
3
2
1
1
2
3
3
3
3
2
2
2
2
2
1
3
 1
3
 2
2
1
 5
2
3
3
1
1
 5
2
2
2
2
2
 6
2
2
2
3
1
3
 5
2
3
3
3
3
 1
2
 100
2
2
1
3
1
3
3
1
1
3
1
1
3
2
1
3
1
1
3
3
2
2
3
1
1
2
3
2
2
3
1
1
2
3
2
1
2
2
3
3
1
1
3
1
2
1
3
1
1
3
2
2
2
1
1
1
3
1
3
2
1
2
2
2
3
3
2
1
1
3
3
2
1
2
1
1
3
1
2
3
2
3
3
3
2
2
1
3
1
2
3
1
2
3
3
1
2
1
3
1
 4
1
2
2
1
 3
3
3
1
 8
1
1
1
1
1
1
1
1
 5
1
1
1
1
3
 3
2
2
3
 3
2
2
2
 2
2
2
 4
2
3
3
3
 2
3
2
 100
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
 7
2
2
2
2
2
2
2
 3
2
1
1
 10
2
3
3
3
3
2
2
2
3
2
 3
3
1
3
 2
3
1
 3
1
2
3
 42
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
 2
1
3
 100
2
3
1
2
3
3
3
1
1
1
1
3
3
3
3
1
2
3
3
3
3
3
3
3
1
2
2
2
3
1
1
3
3
3
3
3
3
3
3
1
2
3
3
3
1
1
1
1
3
3
3
3
1
2
3
1
2
2
2
3
3
2
1
3
3
1
2
3
1
1
1
2
2
2
3
1
1
1
1
1
1
3
2
2
2
2
2
2
3
1
2
2
2
2
2
3
3
2
1
1
 3
3
2
2
 3
3
2
3
 2
3
3
 3
2
2
1
 5
1
1
2
2
3
 3
1
3
1
 3
1
1
3

YES
 NO
 NO
 NO
 YES
 NO
 YES
 YES
 NO
 NO
 NO
 YES
 NO
 NO
 YES
 YES
 YES
 NO
 YES
 YES
 NO
 NO
 NO
 NO
 NO
 YES
 YES
 YES
 NO
 NO
 NO
 YES
 NO
 NO
 NO

import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import java.util.Arrays;
 
 /*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
 
/**
 *
 * @author aman_robotics
 */
public class Main
{

    public static void main(String[] args)throws IOException
    {
        FastReader in=new FastReader(System.in);
        
            int n=in.nextInt();
            int arr[]=new int[n+1];
            for(int i=0;i<n;i++){
                arr[i]=in.nextInt();
            }
            
            int winner=0;
            int looser=0;
            int flag=0;
            int play1=1;
            int play2=2;
            if(n!=1){
            for(int i=0;i<n;i++){
                winner=arr[i];
                if(i!=0){
                    if(arr[i]==looser){
                        flag=1;
                        break;
                    }
                    else{
                        if(winner==1){
                            if((play1==2)||(play2==2)){
                                looser=2;
                                play1=winner;
                                play2=3;
                            }
                            else{
                                looser=3;
                                play1=winner;
                                play2=2;
                            }
                        }
                        else if(winner==2){
                            if(play1==1||play2==1){
                                looser=1;
                                play1=winner;
                                play2=3;
                            }
                            else{
                                looser=3;
                                play1=winner;
                                play2=1;
                            }
                        }
                        else{
                            if(play1==1||play2==1){
                                looser=1;
                                play1=winner;
                                play2=2;
                            }
                            else{
                                looser=2;
                                play1=winner;
                                play2=1;
                            }
                        }
                        //System.out.println(play1+" "+play2);
                    }
                }
                else{
                    play1=winner;
                    looser=2;
                    play2=3;
                    //System.out.println(play1+" "+play2);
                }
            }
            if(flag==1)
            System.out.println("NO");
            else
            System.out.println("YES");
            }
            else{
                if(arr[0]==3)
                System.out.println("NO");
                else
                System.out.println("YES");
            }
    }

    

    
    static class FastReader{
 
        byte[] buf = new byte[2048];
        int index, total;
        InputStream in;
 
        FastReader(InputStream is) {
            in = is;
        }
 
        int scan() throws IOException {
            if (index >= total) {
                index = 0;
                total = in.read(buf);
                if (total <= 0) {
                    return -1;
                }
            }
            return buf[index++];
        }
 
        String next() throws IOException {
            int c;
            for (c = scan(); c <= 32; c = scan());
            StringBuilder sb = new StringBuilder();
            for (; c > 32; c = scan()) {
                sb.append((char) c);
            }
            return sb.toString();
        }
 
        int nextInt() throws IOException {
            int c, val = 0;
            for (c = scan(); c <= 32; c = scan());
            boolean neg = c == '-';
            if (c == '-' || c == '+') {
                c = scan();
            }
            for (; c >= '0' && c <= '9'; c = scan()) {
                val = (val << 3) + (val << 1) + (c & 15);
            }
            return neg ? -val : val;
        }
 
        long nextLong() throws IOException {
            int c;
            long val = 0;
            for (c = scan(); c <= 32; c = scan());
            boolean neg = c == '-';
            if (c == '-' || c == '+') {
                c = scan();
            }
            for (; c >= '0' && c <= '9'; c = scan()) {
                val = (val << 3) + (val << 1) + (c & 15);
            }
            return neg ? -val : val;
        }
    }
} 