#include <iostream>
#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) {
        if (cin.eof()) break;
        double t = (xB - xA) * (xD - xC) + (yB - yA) * (yD - yC);
        if (abs(t) < 1e-9) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }
    return 0;
}