#include<iostream>
#include<cmath>
const double ESP=1e-10;
using namespace std;
int main(){

  double ax,ay,bx,by,cx,cy,dx,dy;
  while(cin>>ax>>ay>>bx>>by>>cx>>cy>>dx>>dy){
    if(fabs((by-ay)*(dy-cy)+(bx-ax)*(dx-cx))<ESP)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;

  }
}