public void checkIfLegal(){
                if (square[2][0] == 19 || square[3][0] == 19) {
                    foreach (List<int> sq in square) {
                        GameBoard.notLegal.Add(Tuple.Create(sq[0], sq[1]));
                    }

                if (GameBoard.notLegal.Any()){
                foreach (Tuple<int, int> pos in GameBoard.notLegal) {
                        if ((square [2] [0] == pos.Item1 && square[2][1] == pos.Item2) || (square [3] [0] == pos.Item1) && square[3][1] == pos.Item2) {
                            temp.Add (Tuple.Create (square [0] [0], square [0] [1]));
                            temp.Add (Tuple.Create (square [1] [0], square [1] [1]));
                            temp.Add (Tuple.Create (square [2] [0], square [2] [1]));
                            temp.Add (Tuple.Create (square [3] [0], square [3] [1]));

                        }
                    }
                }
                GameBoard.notLegal.Union (temp);
                temp.Clear ();
                Reset();
            }
        }