#include <bits/stdc++.h>
using namespace std;

int main()
{
	float  x[4], y[4];

	while (cin >> x[0] >> y[0] >> x[1] >> y[1] >> x[2] >> y[2] >> x[3] >> y[3]){
		float l1, l2;

		l1 = (y[1] - y[0]) / (x[1] - x[0]);
		l2 = (y[3] - y[2]) / (x[3] - x[2]);

		l1 = 1 / l1 * -1;

		if (l1 == l2){
			cout << "YES" << endl;
		}
		else {
			cout << "NO" << endl;
		}

	}

	return (0);
}