#include <bits/stdc++.h>
using namespace std;
int main(void) {
    double xa,ya,xb,yb,xc,yc,xd,yd;
    double EPS=1e-10;
    while (cin>>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd) {
        if (abs( (xd-xc)*(xb-xa)+(yd-yc)*(yb-ya) )<EPS) {
            cout<<"YES"<<endl;
        } else {
            cout<<"NO"<<endl;
        }
    }
}
