using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        //for the given array of points the result should be 2

        var result = new Ray().solution(new Point2D[]{new Point2D{x = -1, y = -2}, new Point2D{x = 1, y = 2}, new Point2D{x = 2, y = 4}, });

        Console.WriteLine(result);

    }

}

​

public class Ray

{

    private Point2D startPoint;

    private Point2D endPoint;

    public Ray()

    {

    }

​

    public Ray(Point2D endPoint)

    {

        this.startPoint = new Point2D{x = 0, y = 0};

        this.endPoint = endPoint;

    }

​

    //do not change the method signature

    public int solution(Point2D[] A)

    {

        List<Ray> rays = new List<Ray>();

        foreach (var point in A)

        {

            if (rays.Count == 0)

            {

                rays.Add(new Ray(point));

            }

            else

            {

                bool isOnLine = false;

                foreach (var ray in rays)

                {

                    if (ray.CheckIsOnLine(point))

                    {

                        isOnLine = true;

                        break;

                    }

                }

​

                if (!isOnLine)

                {

                    rays.Add(new Ray(point));

                }

            }

        }

​

        return rays.Count;

    }

​

    public bool CheckIsOnLine(Point2D point)

    {

        //(x - x_1) / (x_2 - x_1) = (y - y_1) / (y_2 - y_1)

        var isOnSameLine = (startPoint.x - endPoint.x) / (point.x - endPoint.x) == (startPoint.y - endPoint.y) / (point.y - endPoint.y);

        if (isOnSameLine)

        {

            if (point.x > 0 && endPoint.x > 0 || point.x < 0 && endPoint.x < 0 || point.x == 0 && endPoint.x == 0)

            {

                return true;

            }

        }

​

        return false;

    }

}

​

public class Point2D

{

    public long x;

    public long y;

}