#include <iostream>
#include <math.h>
using namespace std;

int main()
{
	double x[4];
	double y[4];
	while (true)
	{
		for (int i = 0; i < 4; i++)
		{
			if (!(cin >> x[i] >> y[i])) return 0;
		}

		double dx1 = x[1] - x[0];
		double dy1 = y[1] - y[0];
		double dx2 = x[3] - x[2];
		double dy2 = y[3] - y[2];
		double innerProduct = (dx1 * dx2) + (dy1 * dy2);

		if (fabs(innerProduct) < 0.00001) cout << "YES" << endl;
		else cout << "NO" << endl;
	}

	return 0;
}