Straight Lines And Pair Of Straight Lines

If \(x^2-y^2+2 h x y+2 g x+2 f y+c=0\) is the locus of a point, which moves such that it is always equidistant from the lines \(x+2 y+7=0\) and \(2 x-y+8=0\), then the value of \(g+c+h-f\) equals