i, n, f, r = 1, int(input()), [1, 1], ['NO', 'YES']
x1, y1 = map(int, input().split())

while i < n and (f[0] or f[1]):
    i += 1
    x, y = map(int, input().split())
    f[0] &= x == x1
    f[1] &= y == y1
    
print(r[f[0] or f[1]])