# AOJ 0058 Orthogonal

while line = gets
  xA, yA, xB, yB, xC, yC, xD, yD = line.split(" ").map {|v| v.to_f}
  vAB = [xB - xA, yB - yA]
  vCD = [xD - xC, yD - yC]

  puts (vAB[0] * vCD[0] + vAB[1] * vCD[1] == 0) ? "YES" : "NO"
end