#include<iostream>
#include<cmath>
using namespace std;
int main(){
    double x1,y1,x2,y2,x3,y3,x4,y4,d;
    while(cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4){
        d=(x2-x1)*(x4-x3)+(y2-y1)*(y4-y3);
        if(abs(d)<1e-13)cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
}