#include <iostream>
#include <cmath>
using namespace std;
 
int main()
{
    double x1,y1,x2,y2,x3,y3,x4,y4;
    while(cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> x4 >> y4){
        if(((x2-x1)*(x4-x3)+(y2-y1)*(y4-y3))/sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1))*sqrt((x4-x3)*(x4-x3)+(y4-y3)*(y4-y3)) == 0)
            cout << "YES" << endl;
        else
            cout << "NO" << endl;
    }
    return 0;
}