#include <iostream>
using namespace std;
int main(void)
{
	double x[4],y[4];
	while(cin >> x[0] >> y[0]){
		for(int i=1; i<4; i++){
			cin >> x[i] >> y[i];
		}
		if( (x[1]-x[0])*(x[3]-x[2])+(y[3]-y[2])*(y[1]-y[0]) == 0 ){
			cout << "YES" << endl;
		}else{
			cout << "NO" << endl;
		}
	}
	return 0;
}