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

int main()
{
	double xa,ya,xb,yb,xc,yc,xd,yd;
	pair<double, double> ab, cd;
	while(cin>>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd){
		ab.first = xb-xa; ab.second = yb-ya;
		cd.first = xd-xc; cd.second = yd-yc;
		if(ab.first*cd.first+ab.second*cd.second) cout<<"NO\n";
		else cout << "YES\n";
	}
	return 0;
}