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

int main()
{
	const double eps = 1e-9;
	double xa,ya,xb,yb,xc,yc,xd,yd;
	while(cin >> xa >> ya >> xb >> yb >> xc >> yc >> xd >> yd){
		if(abs((xb - xa) * (xd - xc) + (yb - ya) * (yd - yc)) <= 0){
			cout << "YES" << endl;
		} else {
			cout << "NO" << endl;
		}
	}
}