#include <bits/stdc++.h>

using namespace std;

using ll = long long;
#define int long long

double dist(double x1, double y1, double x2, double y2){
    return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}

double mn_dst(int ax, int ay, 
              int bx, int by,
              int cx, int cy)
{
    double ox = (bx+cx)/2.0;
    double oy = (by+cy)/2.0;
    double r = dist(ox, oy, bx, by);
    double dst = dist(ox, oy, ax, ay);
    if(r<dst){
        return dst-r;
    }
    else{
        return r-dst;
    }
}

void solve(){
    int ax, ay, bx, by, cx, cy;
    cin>>ax>>ay;
    cin>>bx>>by;
    cin>>cx>>cy;

    cout<<fixed<<setprecision(9)<<min({
        mn_dst(ax, ay, bx, by, cx, cy),
        mn_dst(bx, by, ax, ay, cx, cy),
        mn_dst(cx, cy, bx, by, ax, ay)
    })<<endl;
}

int32_t main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int t=1;
    // cin>>t;
    for(int _=1;_<=t;_++){
        solve();
    }
}