using System;

​

class Point

{

    public float X {get; private set;}

    public float Y {get; private set;}

    public Point(float x, float y)

    {

        X = x;

        Y = y;

    }

}

public class Program

{

    public static void Main()

    {

        Point pt = new Point(1,1);

        Point p1 = new Point(0,0);

        Point p2 = new Point(0,3);

        Point p3 = new Point(4,0);

        Console.WriteLine(PointInTriangle(pt,p1,p2,p3));

    }

    static float sign (Point p1, Point p2, Point p3)

{

    return (p1.X - p3.X) * (p2.Y - p3.Y) - (p2.X - p3.X) * (p1.Y - p3.Y);

}

​

static bool PointInTriangle (Point pt, Point v1, Point v2, Point v3)

{

    float d1, d2, d3;

    bool has_neg, has_pos;

​

    d1 = sign(pt, v1, v2);

    d2 = sign(pt, v2, v3);

    d3 = sign(pt, v3, v1);

​

    has_neg = (d1 < 0) || (d2 < 0) || (d3 < 0);

    has_pos = (d1 > 0) || (d2 > 0) || (d3 > 0);

​

    return !(has_neg && has_pos);

}

}