#include <iostream>

2.#include <cstdio>

3.using namespace std;

4. 

5.struct point

6.{

7.	double x, y;

8.};

9. 

10.int main() {

11.	point p[4];

12.	while (true){

13.		for (int i = 0; i < 4; i++){

14.			if (scanf("%lf%lf", &p[i].x, &p[i].y) == EOF) return 0;

15.		}

16.		//cout << (p[1].x - p[0].x) * (p[3].x - p[2].x) + (p[1].y - p[0].y) * (p[3].y - p[2].y) << endl;

17.		if ((p[1].x - p[0].x) * (p[3].x - p[2].x) + 

18.		    (p[1].y - p[0].y) * (p[3].y - p[2].y) == 0.00){

19.			cout << "YES" << endl;

20.		}

21.		else {

22.			cout << "NO" << endl;

23.		}

24.	}

25.}