#include<iostream>
using namespace std;
int main(){
    double xa,ya,xb,yb,xc,yc,xd,yd;
    while(true){
        if(!(cin>>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd))
            break;

        double d=(yb-ya)/(xb-xa),D=(yd-yc)/(xd-xc);
        d=(1/d)*-1;
        if(d-D<=0.001&&d-D>=-0.001)cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
}