#include <bits/stdc++.h>
using namespace std;


#define ll long long

double dist(double ax, double ay, double bx, double by, double cx, double cy){
    double mx, my;
    mx = (bx+cx)/2.0;
    my = (by + cy)/2.0;

    double dx = mx - cx;
    double dy = my - cy;
    double r = sqrt(dx*dx + dy*dy);

    dx = ax-mx;
    dy = ay-my;

    double r2 = sqrt(dx*dx + dy*dy);
    return abs(r2-r);
}

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


    double ax, ay, bx, by, cx, cy;
    cin >> ax >> ay >> bx >> by >> cx >> cy;

    double da, db, dc;
    da = dist(ax, ay, bx, by, cx, cy);
    db = dist(bx, by, cx, cy, ax, ay);
    dc = dist(cx, cy, ax, ay, bx, by);

    double ans = min(da, min(db, dc));
    cout << ans << "\n";
}