# http://yukicoder.me/problems/433
# No.199 星を描こう

class Point
    attr_accessor :x, :y
    def initialize(x_, y_)
        self.x = x_
        self.y = y_
    end
end

def cross(a, b)
    (a.x * b.y - a.y*b.x)
end

def cross2(a, b, o)
    cross(Point.new(a.x-o.x, a.y-o.y), Point.new(b.x-o.x, b.y-o.y))
end

points = []
N = 5
N.times{
    x, y = gets.split.map(&:to_i)
    points << Point.new(x,y)
}
allok = true
(0...N).each{|i|
    #puts "======= i=#{i} ========="
    o = points[i]
    ok = false
    (0...N).each{|j|
        #puts "  ======= j=#{j} ========="
        if j == i
            next
        end
        a = points[j]
        failed = false
        (0...N).each{|k|
            #puts "    ======= k=#{k} ========="
            if(k==j || k==i)
                next
            end
            b = points[k]
            if cross2(a, b, o)>0
                #puts "cross2 ok"
            else
                failed = true
                #puts "cross2 ng"
            end
        }
        if failed == false
            ok = true
            #puts "ok=true"
        end
    }
    allok &&= ok
}
if allok
    puts "YES"
else
    puts "NO"
end