#include <iostream>
#include<cstdio>
#include <cmath>
using namespace std;
double add1(double x1, double x2, double y1, double y2) {
	return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));

} 
int main() {
double x1, x2, y1, y2, x3, y3;
cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
double  c = add1(x1, y1, x2, y2);
double  a = add1(x1, y1, x3, y3);
double  b = add1(x2, y2, x3, y3);
double  d = a + b + c;
printf("%.2f",d);



}