#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);
       if(abs(t) < 0.0000000001) cout << "YES" << endl;
       else cout << "NO" << endl;
   }
   return 0;
}