using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        var result = new Ray().solution(new Point2D[] {

            new Point2D { x = -1, y = -2 },

            new Point2D { x = 1, y = 2 },

        });

        Console.WriteLine(result);

    }

}

​

public class Ray

{

    //do not change the method signature

    public int solution(Point2D[] A)

    {

            HashSet<decimal> raysDegrees = new HashSet<decimal>();

​

            Parallel.ForEach<Point2D>(A, (point) => 

            {

               decimal rayDegree = RayDegree(point);

               raysDegrees.Add(rayDegree); //HashSet excludes repeatable values, so no need to check if(raysDegrees.Contais(rayDegree))

            });

​

            return raysDegrees.Count();

        }

​

        static decimal RayDegree(Point2D p) => Decimal.Divide(p.x, p.y);

}

​

public class Point2D

{

    public int x;

    public int y;

}