#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <cstdint>
#include <iomanip>
//#include <utility>

int main() {
    double l_ax, l_ay;
    double l_bx, l_by;
    double l_cx, l_cy;

    double l_amidx, l_amidy, l_bmidx, l_bmidy, l_cmidx, l_cmidy;
    double l_alength, l_blength, l_clength;
    double l_amidlength, l_bmidlength, l_cmidlength;

    double l_ashort, l_bshort, l_cshort;

    std::cin >> l_ax >> l_ay;
    std::cin >> l_bx >> l_by;
    std::cin >> l_cx >> l_cy;

    // midpoints
    l_amidx = (l_bx - l_cx) / 2 + l_cx;
    l_amidy = (l_by - l_cy) / 2 + l_cy;

    l_bmidx = (l_cx - l_ax) / 2 + l_ax;
    l_bmidy = (l_cy - l_ay) / 2 + l_ay;

    l_cmidx = (l_bx - l_ax) / 2 + l_ax;
    l_cmidy = (l_by - l_ay) / 2 + l_ay;

    // lengths
    l_alength = sqrt(pow(l_bx - l_cx, 2) + pow(l_by - l_cy, 2));
    l_blength = sqrt(pow(l_cx - l_ax, 2) + pow(l_cy - l_ay, 2));
    l_clength = sqrt(pow(l_bx - l_ax, 2) + pow(l_by - l_ay, 2));


    l_amidlength = sqrt(pow(l_amidx - l_ax, 2) + pow(l_amidy - l_ay, 2));
    l_bmidlength = sqrt(pow(l_bmidx - l_bx, 2) + pow(l_bmidy - l_by, 2));
    l_cmidlength = sqrt(pow(l_cmidx - l_cx, 2) + pow(l_cmidy - l_cy, 2));

    l_ashort = l_amidlength - (l_alength / 2);
    l_bshort = l_bmidlength - (l_blength / 2);
    l_cshort = l_cmidlength - (l_clength / 2);

    // test output
    double l_result = l_cshort;
    if (l_ashort <= l_bshort) {
        if (l_ashort <= l_cshort)
            l_result = l_ashort;
    } else if (l_bshort <= l_cshort) {
        l_result = l_bshort;
    }

    std::cout << std::fixed << std::setprecision(9) << l_result << '\n';
    std::cout << '\n';


    //std::cout << l_ashort << '\n';
    //std::cout << l_bshort << '\n';
    //std::cout << l_cshort << '\n';
}