#include<iostream>
using namespace std;
int main(){
	double a[2],b[2],c[2],d[2];
	while(cin >>a[0]>>a[1]>>b[0]>>b[1]>>c[0]>>c[1]>>d[0]>>d[1]){
		if(a[0] == b[0] && c[1] == d[1]){cout <<"YES"<<endl;}
		else if(a[1] == b[1] && c[0] == d[0]){cout <<"YES"<<endl;}
		else{
			double tab,tcd;
			tab = (a[1]-b[1])/(a[0]-b[0]);
			tcd = (c[1]-d[1])/(c[0]-d[0]);
			if(tab*tcd == -1){cout <<"YES"<<endl;}
			else{cout <<"NO"<<endl;}
		}
	}
	return 0;
}