N = int(input())
P = [ tuple(map(int, input().split())) for _ in range(N) ]

ans = "YES"
x, y = True, True
for i in range(1, N):
    if not x and not y:
        ans = "NO"
        break
    
    if x and P[i][0] != P[i-1][0]:
        x = False
    if y and P[i][1] != P[i-1][1]:
        y = False

print(ans)