main = interact $ unlines . map (orthogonal . map read . words) . lines
orthogonal [xa,ya,xb,yb,xc,yc,xd,yd]
 | xb-xa == 0 = if yd-yc == 0 then "YES" else "NO"
 | xd-xc == 0 = if yb-ya == 0 then "YES" else "NO"
 | (-1) / dab == dcd = "YES"
 | otherwise = "NO"
 where
  dab = (yb-ya)/(xb-xa)
  dcd = (yd-yc)/(xd-xc)