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

int main() {
    double xA, yA, xB, yB, xC, yC, xD, yD;
    while (cin >> xA >> yA >> xB >> yB >> xC >> yC >> xD >> yD) {
        double t = (yB - yA) * (yD - yC) + (xD - xC) * (xB - xA);
        if (t == 0.0) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }
    return 0;
}