#include <iostream>
#include <cmath>

using namespace std;

int main() {
    double x[4], y[4];
    while (1) {
        for (int i = 0; i < 4; i++) {
            if (!(cin >> x[i] >> y[i])) {
                return 0;
            }
        }
        if (abs((x[1] - x[0]) * (x[3] - x[2]) + (y[1] - y[0]) * (y[3] - y[2])) < 1e-10) {
            cout << "YES" << endl;
        }
        else {
            cout << "NO" << endl;
        }
    }

    return 0;
}