#include <iostream>

using namespace std;

int main()
{
	double x[4], y[4];
	
	while ( cin >> x[0] >> y[0] >> x[1] >> y[1] >> x[2] >> y[2] >> x[3] >> y[3] ) {
		if ( (x[1] - x[0]) * (x[3] - x[2]) + (y[1] - y[0]) * (y[3] - y[2]) == 0 ) cout << "YES";
		else cout << "NO";
		cout << endl;
	}
	
	return 0;
}