#include #include using namespace std; const double EPS=1e-10; struct Point{ double x,y,z; Point(double x_=0,double y_=0,double z_=0):x(x_),y(y_),z(z_){} void input(){cin>>x>>y>>z;} Point operator+(Point a){return Point{x+a.x,y+a.y,z+a.z};} Point operator-(Point a){return Point{x-a.x,y-a.y,z-a.z};} Point operator*(double a){return Point{x*a,y*a,z*a};} }; double dot(Point a,Point b){return a.x*b.x+a.y*b.y+a.z*b.z;} Point cross(Point a,Point b){return Point{a.y*b.z-a.z*b.y,a.z*b.x-a.x*b.z,a.x*b.y-a.y*b.x};} double norm(Point a){return dot(a,a);} double abs(Point a){return sqrt(dot(a,a));} double area(Point a,Point b,Point c){return abs(cross(b-a,c-a))/2;} main() { Point p,a,b,c; a.input(); b.input(); c.input(); p.input(); Point h=cross(b-a,c-a); double k=dot(h,a-p)/norm(h); Point x=p+h*k; if(area(x,a,b)+area(x,b,c)+area(x,c,a)>area(a,b,c)+EPS) { cout<<"NO"<