#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;
    if (a < 0) {
        a = -a;
        b = -b;
        c = -c;
        d = -d;
        e = -e;
        f = -f;
    }
    cout << fixed << setprecision(16) << sqrt(4 * a * (f - e) + c * c + d * d) / 2 / a << "\n";
}