#include <iostream>

using namespace std;

int main(void){

  double xa,ya,xb,yb,xc,yc,xd,yd;

  while( cin >> xa >> ya >> xb >> yb >> xc >> yc >> xd >> yd ){
    double x1,x2,y1,y2;

    x1 = xb - xa;
    x2 = xd - xc;
    y1 = yb - ya;
    y2 = yd - yc;  

    if( x1*x2 + y1*y2 == 0 ) cout << "YES" << endl;
    else cout << "NO" << endl;

  }
  return 0;
}