#include <iostream>

using namespace std;

int main(int argc, char **argv)
{
	float xa, ya, xb, yb, xc, yc, xd, yd;
	
	while(cin >> xa >> ya >> xb >> yb >> xc >> yc >> xd >> yd){
		if(((yb-ya)==0.0&&(xd-xc)==0.0)||((xb-xa)==0.0&&(yd-yc)==0.0)){
			cout << "YES" << endl;
		} else if((xb-xa)==0.0&&(xd-xc)==0.0){
			cout << "NO" << endl;
		} else if(((yb-ya)/(xb-xa))*((yd-yc)/(xd-xc)) == -1.0){
			cout << "YES" << endl;
		} else {
			cout << "NO" << endl;
		}
	}
	
	return 0;
}