#include <iostream>

using namespace std;

int main(){
  double x[10],y[10];
  while(cin >> x[1] >> y[1] >> x[2] >> y[2] >> x[3] >> y[3] >> x[4] >> y[4]){
    if((x[4]-x[3])*(x[2]-x[1])+(y[4]-y[3])*(y[2]-y[1]) == 0){
      cout << "YES"<< endl;
    }
    else{
      cout << "NO" << endl;
    }
    
  }
}