#include<iostream>
#include<algorithm>
using namespace std;
int main(void){
  double xa,ya,xb,yb,xc,yc,xd,yd,lx1,lx2,ly1,ly2,a1,a2;
  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;
  }
}
