#coding:utf-8

EPS = 1e-3

class Point
	def initialize(args)
		@x,@y = args[0], args[1]
	end

	def x
		@x
	end
	def y
		@y
	end	

end

while !STDIN.eof? do
	str = gets.chomp.split(' ').map(&:to_f)
	#p str
	a = Point.new(str[0,2])
	b = Point.new(str[2,2])
	c = Point.new(str[4,2])
	p = Point.new(str[6,2])
		
	#外積を求める
	bap = (b.x-a.x)*(p.y-a.y) - (b.y-a.y)*(p.x-a.x)
	cbp = (c.x-b.x)*(p.y-b.y) - (c.y-b.y)*(p.x-b.x) 
	acp = (a.x-c.x)*(p.y-c.y) - (a.y-c.y)*(p.x-c.x) 

	if bap*cbp < 0 || bap*acp<0 || bap*acp<0 then puts "NO"
	else puts "YES"
	end
end