Set<Position> getDiagNeighbors(Position p) {
		Set<Position> neighbors = new HashSet<Position>();		
		if (p.i+1 < n && p.j+1 < m) neighbors.add(board[p.i+1][p.j+1]);
		if (p.i-1 >= 0 && p.j+1 < m) neighbors.add(board[p.i-1][p.j+1]);
		if (p.i+1 < n && p.j-1 >= 0) neighbors.add(board[p.i+1][p.j-1]);
		if (p.i-1 >=0 && p.j-1 >= 0) neighbors.add(board[p.i-1][p.j-1]);
		return neighbors;
	}