#include <iostream>
using namespace std;

int main(){
        double x1,x2,y1,y2,x3,x4,y3,y4;
    
    while(cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> x4 >> y4){
        double a = (y2-y1)/(x2-x1),b = (y4-y3)/(x4-x3);
        if(a*b==-1||(!a||!b)) cout << "YES" << endl;
        else cout << "NO" << endl;
    }
    
    return 0;
}