#include<iostream>
#include<string>
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)==-1*(xb-xa)*(xd-xc)) cout << "YES" << endl;
    else cout << "NO" << endl;
  }
  return 0;
}
 