#include <bits/stdc++.h>

#define rep(i, n) for(int i = 0; i < n; i++)

using namespace std;
using ll = long long;
int mod = 1000000007;

void solve();

int main(void){
    double x1, x2, x3, y1, y2, y3;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    double a1, b1, a2, b2;
    a1 = x2-x1; a2 = x3-x1;
    b1 = y2-y1; b2 = y3-y1;
    double S = fabs(a1*b2-a2*b1)/2;
    double A = sqrt(a1*a1 + b1*b1), B = sqrt(a2*a2 + b2*b2), C = sqrt((a2-a1)*(a2-a1) + (b2-b1)*(b2-b1));
    double r = 2.0*S/(A+B+C);
    double max_edge = max(max(A, B), C);
    printf("%.12f\n", (max_edge*r)/(max_edge + 2.0*r));
    return 0;
}

void solve(){}