#include <iostream>
#include<string>
#include<cmath>
#include<algorithm>
#include<cctype>
#include<queue>
#include<stack>
#include<stdio.h>
#include<vector>
#include<set>
#include<map>
#include<iomanip>
#define rep(i,n) for(int i=0;i<n;i++)
typedef int long long ll;

using namespace std;
int main(){
    double x1,y1,x2,y2,x3,y3,a,b;
    while(cin>>x1){
        cin>>y1>>x2>>y2>>x3>>y3>>a>>b;
        double c=abs((x1-a)*(y2-b)-(x2-a)*(y1-b))/2;
        double d=abs((x2-a)*(y3-b)-(x3-a)*(y2-b))/2;
        double e=abs((x1-a)*(y3-b)-(x3-a)*(y1-b))/2;
        double f=abs((x1-x3)*(y2-y3)-(x2-x3)*(y1-y3))/2;
        if(f==c+d+e){
            cout<<"YES"<<endl;
        }else{
            cout<<"NO"<<endl;
        }
        
        
    }
    
    
    
    return 0;
}

