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

using ll = long long;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using pii = pair<int,int>;
using vll = vector<ll>;
using str = string;
using vstr = vector<string>;

#define PB push_back
#define ALL(x) (x).begin() (x).end()
#define FOR(i,s,f) for(int (i) = (s); i < (f); i++)

#define int long double
long double ans(int a, int b, int x, int y, int c, int d){
    long double g = 0;
    long double strX = (a + x)/2;
    long double strY = (b + y)/2;
    long double rad =  sqrt(pow(strX - a, 2) + pow(strY - b, 2));
    return abs(sqrt(pow(c- strX,2) + pow(d - strY,2)) - rad);
}
main(){
    vi body;
    long double x,y,a,b,c,d;
    cin >>x>>y>>a>>b>>c>>d;

    long double odp = 1e9;
    odp = min(odp, ans(a,b,c,d,x,y));
    odp = min(odp, ans(x,y, a,b,c,d));
    odp = min(odp, ans(c,d,x,y,a,b));
    cout <<setprecision(10) <<abs(odp)<<'\n';
}