#include<iostream>
using namespace std;

int main()
{
    int x1, y1, x2, y2, x3, y3, x4, y4;

    cin >> x1 >> y1 
    	>> x2 >> y2 
    	>> x3 >> y3 
    	>> x4 >> y4;
    
    if (x1 == x2 || x3 == x4)
    {
        cout << "YES!";
    }
    else
    {
        double M1 = (double)(y2 - y1) / (x2 - x1);
        double M2 = (double)(y4 - y3) / (x4 - x3);
        
        if (M1 != M2)
        {
            cout << "YES!";
        }
        else
        {
            cout << "NO";
        }
    }

    return 0;
}