#include <bits/stdc++.h>

using namespace std; 
using ll = long long;
#define ff first
#define ss second
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	double x1, x2, x3, y1, y2, y3;
	cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
	double xc1, xc2, yc1, yc2, xc3, yc3;
	xc1 = (x2+x3)/2;
	xc2 = (x1+x3)/2;
	xc3 = (x2+x1)/2;
	yc1 = (y2+y3)/2;
	yc2 = (y1+y3)/2;
	yc3 = (y2+y1)/2;
	double r1, r2, r3;
	r1 = sqrt((x2-x3)*(x2-x3)+(y3-y2)*(y3-y2))/2;
	r2 = sqrt((x1-x3)*(x1-x3)+(y3-y1)*(y3-y1))/2;
	r3 = sqrt((x2-x1)*(x2-x1)+(y1-y2)*(y1-y2))/2;
	
	double distp1, distp2, distp3;
	distp1 = sqrt((x1-xc1)*(x1-xc1)+(y1-yc1)*(y1-yc1));
	distp2 = sqrt((x2-xc2)*(x2-xc2)+(y2-yc2)*(y2-yc2));
	distp3 = sqrt((x3-xc3)*(x3-xc3)+(y3-yc3)*(y3-yc3));
	double ans = min({abs(distp1-r1), abs(distp2-r2), abs(distp3-r3)});
	cout << fixed << setprecision(9);
	cout << ans << '\n';
	return 0;
	}