#include<iostream>
using namespace std;

int main(){
	float xa,ya,xb,yb,xc,yc,xd,yd;

	while(cin>>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd){
		if( (xb-xa) * (xd-xc) + (yb-ya) * (yd-yc) == 0.0)
			cout << "YES" << endl;
		else cout << "NO" << endl;
	}
	return 0;
}