#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;
double a,b,c,d,e,f;
double fun(double a,double b,double c,double d)
{
	return sqrt(pow(a-c,2)+pow(b-d,2));
}
int main()
{
	cin>>a>>b>>c>>d>>e>>f;
	cout<<fixed<<setprecision(2)<<fun(a,b,c,d)+fun(c,d,e,f)+fun(e,f,a,b);
}