#include <iostream>
#include <cmath>

using namespace std;

void solve()
{
	double x[4], y[4];
	while(cin >> x[0] >> y[0])
	{
		for(int i = 1; i < 4; ++i)
		{
			cin >> x[i] >> y[i];
		}
		if((x[0] == x[1] && y[0] == y[1]) || (x[2] == x[3] && y[2] == y[3]))
		{
			cout << "NO" << endl;
		}
		else if((x[0] == x[1] && y[0] != y[1]) && (x[2] != x[3] && y[2] == y[3]))
		{
			cout << "YES" << endl;
		}
		else if((x[0] != x[1] && y[0] == y[1]) && (x[2] == x[3] && y[2] != y[3]))
		{
			cout << "YES" << endl;
		}
		else if(x[0] != x[1] && x[2] != x[3] && fabs((y[1] - y[0]) * (y[3] - y[2]) + (x[1] - x[0]) * (x[3] - x[2])) < 0.000000001)
		{
			cout << "YES" << endl;
		}
		else
		{
			cout << "NO" << endl;
		}
	}
}

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