If the sum of squares of all real values of \( \alpha \), for which the lines \( 2x - y + 3 = 0 \), \( 6x + 3y + 1 = 0 \) and \( a x + 2y - 2 = 0 \) do not form a triangle is \( p \), then the greatest integer less than or equal to \( p \) is __________.
