#include <cmath>
#include <iostream>
using namespace std;
double xa, ya, xb, yb, xc, yc, xd, yd;
int main() {
	while(cin >> xa >> ya >> xb >> yb >> xc >> yc >> xd >> yd) {
		xb -= xa, yb -= ya;
		xd -= xc, yd -= yc;
		if(abs(xb * xd + yb * yd) < 1.0e-12) cout << "YES" << endl;
		else cout << "NO" << endl;
	}
	return 0;
}
