#include<iostream>
int main()
{
	while (true)
	{
		long double x[4], y[4];
		for (int i = 0; i < 4; i++)
		{
			std::cin >> x[i] >> y[i];
		}
		if (std::cin.eof())
		{
			break;
		}
		std::cout << (y[0] == y[1] && x[2] == x[3] || y[2] == y[3] && x[0] == x[1] || (y[1] - y[0]) / (x[1] - x[0]) * (y[3] - y[2]) / (x[3] - x[2]) == -1 ? "YES" : "NO") << std::endl;
	}
	return 0;
}
