#include <iostream>
#include <cmath>
#include <stdio.h>
#include <algorithm>
using namespace std;
double EPS=1e-10;
double add(double a, double b)
{
	if(abs(a+b)<EPS*(abs(a)+abs(b))) return 0;
	return a+b;
}
int main()
{
	double x[4],y[4];
	while(cin>>x[0]>>y[0]>>x[1]>>y[1]>>x[2]>>y[2]>>x[3]>>y[3])
	{
		double vx[2],vy[2];
		for(int i=0;i<2;i++)
		{
			vx[i]=x[2*i+1]-x[2*i];
			vy[i]=y[2*i+1]-y[2*i];
		}
		if(add(vx[0]*vx[1],vy[0]*vy[1])==0) cout << "YES" << '\n' ;
		else cout << "NO" << '\n' ;
	}
}