#include <iostream>
#include <math.h>
using namespace std;
int main(){
	double xa,ya,xb,yb,xc,yc,xd,yd;
	int a;
	while(cin>>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd){
		if(xa==xb){
			if(yc==yd) a=1;
			else a=2;
		}else if(xc==xd){
			if(ya==yb) a=1;
			else a=2;
		}else{
			double l=(yb-ya)/(xb-xa);
			double m=(yd-yc)/(xd-xc);
			if(fabs(l*m+1)<0.000001) a=1;
			else a=2;
		}
		switch(a){
		case 1:
			cout<<"YES"<<endl;
			break;
		case 2:
			cout<<"NO"<<endl;
			break;
		}
	}
	return 0;
}