#include <iostream>
#include <algorithm>
#include <complex>
using namespace std;

typedef complex<double> P;

const double eps = 1e-8;

bool equals(double a, double b) {
  return abs(a-b) < eps;
}

double dot(P a, P b) {
  return a.real()*b.real() + a.imag()*b.imag();
}

int main() {
  P ps[4];
  while(1) {
    for(int i = 0; i < 4; ++i) {
      if(cin >> ps[i].real() >> ps[i].imag()) ; else return 0;
    }
    if(equals(dot(ps[0]-ps[1], ps[2]-ps[3]), 0.0)) {
      cout << "YES" << endl;
    } else {
      cout << "NO" << endl;
    }
  }
  return 0;
}