#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void process() {
    ll ax, ay, bx, by, cx, cy;
    cin >> ax >> ay >> bx >> by >> cx >> cy;

    double sabx, saby, sacx, sacy, sbcx, sbcy;
    sabx = ((double) ax + (double) bx) / 2;
    saby = ((double) ay + (double) by) / 2;
    sacx = ((double) ax + (double) cx) / 2;
    sacy = ((double) ay + (double) cy) / 2;
    sbcx = ((double) bx + (double) cx) / 2;
    sbcy = ((double) by + (double) cy) / 2;

    double cDist = sqrt( pow((sabx - (double) cx), 2) + pow((saby - (double) cy), 2) );
    double cCost = cDist - sqrt( pow((double) ax - sabx, 2) + pow((double) ay - saby, 2) );
    cCost = abs(cCost);

    double bDist = sqrt( pow((sacx - (double) bx), 2) + pow((sacy - (double) by), 2) );
    double bCost = bDist - sqrt( pow((double) ax - sacx, 2) + pow((double) ay - sacy, 2) );
    bCost = abs(bCost);

    double aDist = sqrt( pow((sbcx - (double) ax), 2) + pow((sbcy - (double) ay), 2) );
    double aCost = aDist - sqrt( pow((double) bx - sbcx, 2) + pow((double) by - sbcy, 2) );
    aCost = abs(aCost);

    cout << min({ cCost, bCost, aCost }) << "\n";
}

int main() {
    std::ios::sync_with_stdio(false);
    process();
    cout.flush();
    return 0;
}