#include<iostream>

using namespace std;

int main(){


  double x[4], y[4], kata[2];

  while(cin >>x[0]>>y[0]>>x[1]>>y[1]>>x[2]>>y[2]>>x[3]>>y[3]){
    if(x[0] - x[1] != 0 && x[2] - x[3] != 0){
      kata[0] = (y[0] - y[1]) / (x[0] - x[1]);
      kata[1] = (y[2] - y[3]) / (x[2] - x[3]);

      if(kata[0] * kata[1] == -1) cout << "YES" << endl;
      else cout << "NO" << endl;

    }else{
      if(x[0] - x[1] == 0 && y[2] - y[3] == 0 || y[0] - y[1] == 0 && x[2] - x[3] == 0) cout << "YES" << endl;
      else cout <<"NO"<<endl;
	
    }
  }

  return 0;
  
}