public boolean validMove(int dir) {
		
		boolean valid = true;
		int[][] key = screen[row][col].key();
		
		if (col+dir < 0 || col+dir >= NUM_COLS || dead[row][col+dir] == true)
			valid = false;
		for (int i=0; i<3; i++) {
			int r = row+key[i][0];
			int c = col+key[i][1];
			if (c+dir < 0 || c+dir >= NUM_COLS || dead[r][c+dir] == true)
				valid = false;
		}
			
		return valid;
	}