#include<iostream>
#include<cmath>
using namespace std;

int main(){
    double x1, x2, x3, x4, y1, y2, y3, y4;
    while(cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> x4 >> y4){
        if (abs(((x2 - x1) * (x4 - x3)) + ((y2 - y1) * (y4 - y3))) < 1e-9) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }
}