#include <iostream>
using namespace std;

int main(){
	double xa, ya;
	double xb, yb;
	double xc, yc;
	double xd, yd;
	while(cin >> xa >> ya >> xb >> yb
		>> xc >> yc >> xd >> yd)
	{
		double dx1 = xb - xa, dy1 = yb - ya;
		double dx2 = xd - xc, dy2 = yd - yc;
		if(dx1 * dx2 + dy1 * dy2 == 0){
			cout << "YES" << endl;
		} else {
			cout <<"NO" << endl;
		}
	}
	return 0;
}