#include <iostream>

using namespace std;

int main()
{
	double p[4][2], dot;

	while (1) {
		for (int i = 0; i < 4; i++) {
			cin >> p[i][0] >> p[i][1];
		}
		if (cin.eof())	break;

		dot = ((p[0][0] - p[1][0]) * (p[2][0] - p[3][0])) + ((p[0][1] - p[1][1]) * (p[2][1] - p[3][1]));

		if (dot < 0.00000001) {
			cout << "YES" << endl;
		}
		else{
			cout << "NO" << endl;
		}
	}
}