#include <iostream>

using namespace std;

void solve()
{
	double x1, y1, x2, y2, x3, y3, x4, y4;
	while(cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> x4 >> y4)
	{
		if((x1 == x2 && y3 == y4) || (y1 == y2 && x3 == x4))
		{
			cout << "YES" << endl;
		}
		else if(x1 == x2 || x3 == x4)
		{
			cout << "NO" << endl;
		}
		else if(((y2 - y1) / (x2 - x1)) * ((y4 - y3) / (x4 - x3)) == -1)
		{
			cout << "YES" << endl;
		}
		else
		{
			cout << "NO" << endl;
		}
	}
}

int main()
{
	solve();
	return(0);
}