#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) {
    double dx1 = xb - xa, dy1 = yb - ya;
    double dx2 = xd - xc, dy2 = yd - yc;
    if(dx1 * dx2 + dy1 * dy2 == 0)
      cout <<"YES"<<endl;
    else
      cout <<"NO"<<endl;
  }
  return 0;
}