#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; i++)
using namespace std;

typedef long long ll;

int main() {
    double a, b, c, d, e, f;
    cin >> a >> b >> c >> d >> e >> f;
    cout << fixed << setprecision(8) << sqrt((4 * a * (f - e) + c * c + d * d) / (4 * a * a)) << "\n";
}