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

n = int(input())
a = []
for i in range(n):
    x = int(input())
    a.append(x)
flag = True
p1, p2 = 1, 2
for x in a:
    if x != p1 and x != p2:
        flag = False
        break
    else:
        if x == p1:
            p2 = 6  - p1 - p2
        else:
            p1 = 6 - p1 - p2
print("YES" if flag else "NO")

    	 		 		  		 		 	 	 			    	