#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){
    if((yb-ya)*(yd-yc)+(xb-xa)*(xd-xc)<1E-6) cout<<"YES";
    else cout<<"NO";
    cout<<endl;
  }
  return 0;
}