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

int main()
{
	double x1,x2,x3,x4,y1,y2,y3,y4;
	while(cin >> x1)
	{
		cin >> y1 >> x2 >> y2 >> x3 >> y3 >> x4 >> y4;

		x2 -= x1; y2 -= y1;
		x4 -= x3; y4 -= y3;

		cout << ( fabs(x2*x4+y2*y4)<1e-10 ? "YES" : "NO") << endl;

	}
}