#include "math.h"
#include "stdio.h"
#include <algorithm>
#include <string>
#include <iostream>

using namespace std;

/** Problem0058 : Orthogonal **/
int main()
{
	double xA, yA, xB, yB, xC, yC, xD, yD, EPS=1e-12;
	
	while (cin >> xA >> yA >>xB >> yB >> xC >> yC >> xD >> yD) {
		if (fabs((xB-xA)*(xD-xC)+(yB-yA)*(yD-yC))<EPS)
			cout << "YES" << endl;
		else
			cout << "NO" << endl;
	}
	return 0;
}