#include <iostream>
using namespace std;
int main()
{
	int i;
	double x[4], y[4];

	while(1)
	{
		cin >> x[0];
		if (cin.eof())return 0;
		cin >> y[0];
		for (i = 1; i < 4; i++)
			cin >> x[i] >> y[i];
		if ((y[1]-y[0])/(x[1]-x[0])*(y[3]-y[2])/(x[3]-x[2])==-1||((x[1]-x[0])==0&&(x[3]-x[2])==0))
			cout << "YES" << endl;
		else
			cout << "NO" << endl;
	}
	return 0;
}