#include <iostream>
#include <cmath>
using namespace std;

int main(){
   double xA, yA, xB, yB, xC, yC, xD, yD;
   while(cin >> xA >> yA >> xB >> yB >> xC >> yC >> xD >> yD){
       double t = (yA-yB)*(yC-yD) + (xC-xD)*(xA-xB);
       cout << (abs(t) < 1e-9 ? "YES" : "NO") << endl;
   }
   return 0;
}