#include<iostream>
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 xab = xb - xa, yab = yb - ya;
        double xcd = xd - xc, ycd = yd - yc;

        double inner_product = xab * xcd + yab * ycd;

        if( inner_product < 1.0e-15 )           //1.0e-15の誤差を考慮。
            cout << "YES" << endl;
        else
            cout << "NO" << endl;
    }

    return 0;
}
