#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<ll>;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int x1, y1, x2, y2, x3, y3;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;

    double mini = 10000000.0;

    double x_mid, y_mid, dy, dx, r, dist;

    x_mid = min(x1, x2) + (abs(x1 - x2) / 2.0);
    y_mid = min(y1, y2) + (abs(y1 - y2) / 2.0);

    r = hypot(x1 - x2, y1 - y2) / 2.0;
    dist = hypot(x_mid - x3, y_mid - y3);

    mini = min(mini, abs(dist-r));

    x_mid = min(x3, x2) + (abs(x3 - x2) / 2.0);
    y_mid = min(y3, y2) + (abs(y3 - y2) / 2.0);

    r = hypot(x3 - x2, y3 - y2) / 2.0;
    dist = hypot(x_mid - x1, y_mid - y1);

    mini = min(mini, abs(dist-r));


    x_mid = min(x3, x1) + (abs(x3 - x1) / 2.0);
    y_mid = min(y3, y1) + (abs(y3 - y1) / 2.0);

    r = hypot(x3 - x1, y3 - y1) / 2.0;
    dist = hypot(x_mid - x2, y_mid - y2);

    mini = min(mini, abs(dist-r));


    cout << fixed << setprecision(9) << mini << endl;

    return 0;
}