#include <iostream>
#include <string>
#include <math.h>
#include <algorithm>


using namespace std;
int main(){

    double xA, yA, xB, yB, xC, yC, xD, yD;
    while(cin>>xA>>yA>>xB>>yB>>xC>>yC>>xD>>yD){
        double tan1 = atan((yA-yB)/(xA-xB));
        double tan2 = atan((yC-yD)/(xC-xD));
        
        double deg = (tan1-tan2)*180/M_PI;
        //cout<<deg<<endl;
        if(deg==-90||deg==90)cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
}