#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	double a, b, c, d, e, f;
	cin >> a >> b >> c >> d >> e >> f;
	double x = c / a / 2;
	double y = d / a / 2;
	double r2 = f / a - e / a + x * x + y * y;
	cout << fixed << setprecision(12) << sqrt(r2) << endl;
}