#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;


double distance(double x1, double x2, double y1, double y2)
{
    return sqrtf(pow(x1 - y1, 2) +  pow(x2 - y2, 2));
}

pair<double, double> midpoint(double x1, double x2, double y1, double y2)
{
    pair<double, double> pt;
    pt.first = x1 + (y1 - x1) / 2; 
    pt.second = x2 + (y2 - x2) / 2; 
    return pt;
}

int main()
{
    ios::sync_with_stdio(false); cin.tie(nullptr);
    pii a, b, c;
    cin >> a.first >> a.second >> b.first >> b.second >> c.first >> c.second;
    double best = numeric_limits<int>::max();
    // 3 lines
    double dist, r;
    pair<double, double> mid;

    // AB
    mid = midpoint(a.first, a.second, b.first, b.second);
    r = distance(a.first, a.second, b.first, b.second) / 2;
    dist = distance(mid.first, mid.second, c.first, c.second);

    if (dist >= r)
        best = min(best, dist - r);
    else 
        best = min(best, r - dist);
    
    //cout << best << endl;
    // AC
    mid = midpoint(a.first, a.second, c.first, c.second);
    r = distance(a.first, a.second, c.first, c.second) / 2;
    dist = distance(mid.first, mid.second, b.first, b.second);

    if (dist >= r)
        best = min(best, dist - r);
    else 
        best = min(best, r - dist);

    //scout << best << endl;

    // BC
    mid = midpoint(b.first, b.second, c.first, c.second);
    r = distance(b.first, b.second, c.first, c.second) / 2;
    dist = distance(mid.first, mid.second, a.first, a.second);

    if (dist >= r)
        best = min(best, dist - r);
    else 
        best = min(best, r - dist);

    //cout << best << endl;


    cout << best << endl;
    
}