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

int main(){
	double x1,x2,x3,x4,y1,y2,y3,y4,EPS=1e-12;
	while(cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4){
		if(fabs(((x2-x1)*(x4-x3))+((y2-y1)*(y4-y3)))<=EPS)cout<<"YES";
		else cout<<"NO";
		cout<<endl;
	}
}