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

#define EPS 1.0e-10

int main()
{
	double xa,ya,xb,yb,xc,yc,xd,yd;
	while(cin>>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd){
		if(abs((xb-xa)*(xd-xc)+(yb-ya)*(yd-yc)) < EPS) cout<<"YES"<<endl;
		else cout << "NO" << endl;
	}
	return 0;
}