#include<iostream>
using namespace std;
int main()
{
  while(1){
    double xa,ya,xb,yb,xc,yc,xd,yd;
    cin >>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd;
    if(cin.eof()){
      break;
    }
    double abx = xb-xa;
    double aby = yb-ya;
    double cdx = xd-xc;
    double cdy = yd-yc;
    if(abx*cdx+aby*cdy==0)
      cout <<"YES"<<endl;
    else
      cout <<"NO"<<endl;
  }
  return 0;
}