#include<iostream>
#include<cstdio>
#include<cmath>

using namespace std;

struct xy
{
	double x;
	double y;
};

double longa(double a1,double b1,double a2,double b2)
{
	return sqrt(pow(a1-b1,2)+pow(a2-b2,2));
}
int main()
{
	double sum=0;
	xy p[3];
	for(int i=0;i<3;i++)
		cin>>p[i].x>>p[i].y;
	sum+=longa(p[0].x,p[0].y,p[1].x,p[1].y);
	sum+=longa(p[0].x,p[0].y,p[2].x,p[2].y);
	sum+=longa(p[1].x,p[1].y,p[2].x,p[2].y);
	printf("%.2lf",sum);
	return 0;
}