#include <iostream>
#include <cmath>
#define EPS 1e-9
using namespace std;
int main(void){
  double xa,ya,xb,yb,xc,yc,xd,yd;
  while(cin>>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd){
	  if(fabs((ya-yb)*(yc-yd)+((xa-xb)*(xc-xd))) <= EPS)cout<<"YES"<<endl;
	  else cout<<"NO"<<endl; 
  }
  return 0;
}