//50
#include<iostream>

using namespace std;

int main(){
  for(;;){
    double x[4],y[4];
    for(int i=0;i<4;i++){
      cin>>x[i]>>y[i];
      if(!cin)return 0;
    }
    cout<<(((x[1]-x[0])*(x[3]-x[2])+(y[1]-y[0])*(y[3]-y[2])!=0)?"NO":"YES")<<endl;
  }
  return 0;
}