a

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
struct Point {
    double x, y;
};
double distance(const Point& p1, const Point& p2) {
    double dx = p2.x - p1.x;
    double dy = p2.y - p1.y;
    return sqrt(dx * dx + dy * dy);
}
int main() {
    Point p1, p2, p3;
    cin >> p1.x >> p1.y;
    cin >> p2.x >> p2.y;
    cin >> p3.x >> p3.y;
    double a = distance(p1, p2);
    double b = distance(p2, p3);
    double c = distance(p3, p1);
    double perimeter = a + b + c;
    cout << fixed << setprecision(2) << perimeter << endl;
}