#include <iostream>
#include <bits/stdc++.h>

using namespace std;

int main()
{

/*
    int t;
    cin >> t;
    while(t--){
        int a,b,c;
        cin >> a >> b >> c;
        int mx = max(a,max(b,c));
        int mn = min(a,min(b,c));
        int md = a+b+c-mx-mn;
        if(mn % 10 == 0 && md % 10 == 0){
            cout << "NO" << endl;
            continue;
        }
        if(mx != mn*md){
            cout << "NO" << endl;
            continue;
        }
        vector<int> v;
        for(int i = 0; i <= 11; i++){
            v.push_back(0);
        }
        int aa = 0, bb = 0, cc = 0;
        while (mx > 0){
            int x = mx%10;
            v[x]++;
            mx/=10;
            aa++;
        }
        while (mn > 0){
            int x = mn%10;
            v[x]--;
            mn/=10;
            bb++;
        }
        while (md > 0){
            int x = md%10;
            v[x]--;
            md/=10;
            cc++;
        }
        if(bb!=cc || aa/2 != bb){
            cout << "NO" << endl;
            continue;
        }
        int flag = 0;
        for(int i = 0; i <= 11; i ++){
            if(v[i]!= 0){
                flag = 1;
                cout << "NO" << endl;
                break;
            }
        }
        if(flag == 1){
            continue;
        }
        cout << "YES" << endl;
    }
    */

    double x1,x2,x3,y1,y2,y3;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    double s1,s2,s3;
    s1 = abs(sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)) / 2 - sqrt(((x1 + x2) / 2 - x3) * ((x1 + x2) / 2 - x3) + ((y1 + y2) / 2 - y3) * ((y1 + y2) / 2 - y3)));
    swap(x2, x3);
    swap(y2, y3);
    s2 = abs(sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)) / 2 - sqrt(((x1 + x2) / 2 - x3) * ((x1 + x2) / 2 - x3) + ((y1 + y2) / 2 - y3) * ((y1 + y2) / 2 - y3)));
    swap(x1, x3);
    swap(y1, y3);
    s3 = abs(sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)) / 2 - sqrt(((x1 + x2) / 2 - x3) * ((x1 + x2) / 2 - x3) + ((y1 + y2) / 2 - y3) * ((y1 + y2) / 2 - y3)));
    //cout << s1 << endl << s2 << endl << s3 << endl;
    cout << min(s1, min(s2, s3));
}