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

double EPS = 1e-12;

int main(void)
{
	double x1, x2, x3, x4, y1, y2, y3, y4;
	while (cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4){
		if (fabs(((x2-x1)*(x4-x3))+((y2-y1)*(y4-y3))) <= EPS) cout << "YES" << endl;
		else cout << "NO" << endl;
	}
	
	return 0;
}