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

int main(){

	double xa, ya, xb, yb, xc, yc, xd, yd;

	while (cin >> xa >> ya >> xb >> yb >> xc >> yc >> xd >> yd){
		if ((yb - ya)*(yd - yc) + (xd - xc)*(xb - xa) == 0 )
		{
			cout << "YES" << endl;
		}
		else
		{
			cout << "NO" << endl;
		}

	}
	return 0;
}