#include <iostream>
#include <cmath>

using namespace std;

constexpr double EPS = 0.0000000001;

int main()
{
    double xA, yA, xB, yB, xC, yC, xD, yD;

    while (cin >> xA >> yA >> xB >> yB >> xC >> yC >> xD >> yD) {
        double dot = (yA-yB) * (yC-yD) + (xC-xD) * (xA-xB);

        if (abs(dot) < EPS) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }

    return 0;
}