#include<iostream>
#include<cmath>
#include<complex>
#define EPS 10e-9
using namespace std;
typedef complex<double> p;
int main()
{
	p a,b,c,d;
	while(cin>>a.real()>>a.imag()>>b.real()>>b.imag()>>c.real()>>c.imag()>>d.real()>>d.imag())
	{
		if( abs((b-a).real()*(d-c).real()+(b-a).imag()*(d-c).imag()) < EPS ) cout<<"YES"<<endl;
		else cout<<"NO"<<endl;
	}
  return 0;
}