private void Process()
        {
            foreach(TestCase tc in _lstTestCases)
            {
                foreach(Atrraction attraction in _lstAttractions)
                {
                    PointD p1 = new PointD(tc.Longitude, tc.Latitude);
                    PointD p2 = new PointD(attraction.Longitude, attraction.Latitude);
                    double distance = Math.Round(DistanceBetween(p1,p2), 2);

                    double speed = 0;

                    switch(tc.PreferredTransport)
                    {
                        case __METRO:
                            speed = _METROSPEED_;
                            break;
                        case __BIKE:
                            speed = _BIKESPEED_;
                            break;
                        case __FOOT:
                            speed = _FOOTSPEED_;
                            break;
                    }

                    if(distance/speed <= tc.Minutes)
                    {
                        _dictSelectedAttractions.Add(attraction.Id, distance);
                    }
                }
                var sortedDict = from entry in _dictSelectedAttractions orderby entry.Value ascending select entry.Key;
                Console.WriteLine(string.Join(" ", sortedDict.ToArray()));
                _dictSelectedAttractions.Clear();
            }
        }
        protected double DistanceBetween(PointD p1, PointD p2)
        {
            int EARTH_RADIUS = 6371;//in km 
            
            double point1_lat_in_radians  = Degree2Radians(p1.Y);
            double point2_lat_in_radians = Degree2Radians(p2.Y);
            double point1_long_in_radians = Degree2Radians(p1.X);
            double point2_long_in_radians = Degree2Radians(p2.X);

            return Math.Acos( Math.Sin( point1_lat_in_radians ) * Math.Sin( point2_lat_in_radians ) +
                 Math.Cos(point1_lat_in_radians) * Math.Cos(point2_lat_in_radians) *
                 Math.Cos(point2_long_in_radians - point1_long_in_radians)) * EARTH_RADIUS;
        }