#include <iostream>
using namespace std;
typedef struct {double x, y;} POINT;
int main()
{
	POINT a, b, c, d;
	double m1, m2;
	while (cin >> a.x >> a.y >> b.x >> b.y >> c.x >> c.y >> d.x >> d.y)
	{
		if (!(a.x - b.x == 0 && c.x - d.x == 0))
		{
			if ((a.x - b.x == 0 && c.y - d.y == 0) || (a.y - b.y == 0 && c.x - d.x == 0))
			{
				cout << "YES" << endl;
				continue;
			}
			else if (((a.y - b.y) / (a.x - b.x)) * ((c.y - d.y) / (c.x - d.x)) == -1.0)
			{
				cout << "YES" << endl;
				continue;
			}
		}
		cout << "NO" << endl;
	}
}