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#include <iostream>
#include <cmath>
using namespace std;
double distance(double x1, double y1, double x2, double y2) {
return sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2));
}

int main() {
double x1, y1, x2, y2, x3, y3;
cin >> x1 >> y1;
cin >> x2 >> y2;
cin >> x3 >> y3;
double side1 = distance(x1, y1, x2, y2);
double side2 = distance(x2, y2, x3, y3);
double side3 = distance(x3, y3, x1, y1);
double perimeter = side1 + side2 + side3;
cout << fixed;
cout.precision(2);
cout << perimeter << endl;
return 0;
}