#include <iostream>

using namespace std;

int main(){
  double x1,x2,x3,x4,y1,y2,y3,y4;
  while( cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> x4 >> y4){
    double m,n;
      m = (y1 - y2)/(x1 - x2);
      n = (y3 - y4)/(x3 - x4);
      if(m*n == -1 ||
	 (x1 == x2 && y3 == y4)||
	 (y1 == y2 && x3 == x4))cout << "YES" << endl;
      else cout << "NO" << endl;
  }
}