def sp(l):
    l = list(map(int, l))
    return l[:2], l[2:]

n = int(input())
a, b, c = [2, 8], [3, 9], [7, 9]

for _ in "_"*n:
    d, s = sp(input().split())
    if d == a:
        a = s
    elif d == b:
        b = s
    elif d == c:
        c = s

print("YNEOS"[a!=[5, 8] and b!=[4, 8] and c!=[6, 8]::2])