#include<iostream>
#include<algorithm>
#include<cstdio>

using namespace std;

float hang(float a,float b,float c,float d,float e,float f){
    float A;
    A=(a*d + b*e + c*f - e*d - b*c - a*f)/2;
    return A;      
}

int main()
{
    float x1,y1,x2,y2,x3,y3,xp,yp,s1,s2,s3,s;
    while(cin>>x1>>y1>>x2>>y2>>x3>>y3>>xp>>yp){
       s1=hang(xp,yp,x2,y2,x3,y3);
       s2=hang(x1,y1,xp,yp,x3,y3);
       s3=hang(x1,y1,x2,y2,xp,yp);
       s=hang(x1,y1,x2,y2,x3,y3);
       if(s==(s1+s2+s3))cout<<"YES"<<endl;
       else cout<<"NO"<<endl;                                                   
    }
    return 0;
}