#include <iostream>
#include <cmath>

using namespace std;

#define EPS (1e-10)

int main()
{
    double xa, xb, xc, xd;
    double ya, yb, yc, yd;

    while (cin >> xa >> ya >> xb >> yb
           >> xc >> yc >> xd >> yd) {
        xb -= xa;
        yb -= ya;
        xd -= xc;
        yd -= yc;

        if (abs(xb * xd + yb * yd) < EPS)
            cout << "YES" << endl;
        else
            cout << "NO" << endl;
    }
    
    return 0;
}