#include <iostream>
using namespace std;

int main() {
  double xA,yA,xB,yB,xC,yC,xD,yD;
  double inner,vecAB[2],vecCD[2];
  while (cin >> xA >> yA >> xB >> yB >> xC >> yC >> xD >> yD) {
    vecAB[0] = xB - xA;
    vecAB[1] = yB - yA;
    vecCD[0] = xD - xC;
    vecCD[1] = yD - yC;
    inner = vecAB[0] * vecCD[0] + vecAB[1] * vecCD[1];
    if(inner == 0)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
}