#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> pll;

#define For(i, a, n) for(ll i=a;i<n;i++)
#define vec vector
#define sz(x) (ll)x.size()
#define all(x) begin(x), end(x)


template<typename... Args>
void dbg(Args&&... args){
    ((cerr<<args<<" |"),...);
    cerr<<endl;
}

double f(pll a, pll b, pll other){
    //dbg(a.first,a.second,b.first,b.second,other.first,other.second);
    double centerx = (a.first+b.first)/(double)2;
    double centery = (a.second+b.second)/(double)2;
    double c_to_center = sqrt((other.first - centerx)*(other.first - centerx)+(other.second - centery)*(other.second - centery));
    double a_to_b = sqrt((a.first-b.first)*(a.first-b.first)+(a.second-b.second)*(a.second-b.second));
    //dbg(centerx, centery, c_to_center, a_to_b);
    return abs(c_to_center - a_to_b/2);
}

void solve(){

    pll a,b,c;
    cin >> a.first >> a.second;
    cin >> b.first >> b.second;
    cin >> c.first >> c.second;

    //dbg(f(a,b,c),f(b,c,a),f(c,a,b));

    cout << setprecision(7) << fixed;

    cout << min(f(a,b,c),min(f(b,c,a),f(c,a,b))) << endl;
    
}

int main(){
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    ll t = 1;//cin>>t;
    while(t--)solve();
}