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#include <cstdio>
#include<iostream>
#include<cmath>
using namespace std;

inline double fast_dist(double dx, double dy) {
    return sqrt(dx*dx + dy*dy);
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    double x[3], y[3];
    cin >> x[0] >> y[0] >> x[1] >> y[1] >> x[2] >> y[2];
    
    double a = fast_dist(x[0]-x[1], y[0]-y[1]);
    double b = fast_dist(x[1]-x[2], y[1]-y[2]);
    double c = fast_dist(x[2]-x[0], y[2]-y[0]);
    
    printf("%.2f",a+b+c);
    return 0;
}