#include<bits/stdc++.h>
#include<cmath>
using namespace std;
int a,b,c,d,e,f;
double s1,s2,s3;
int main()
{
	cin >> a >> b >> c >> d >> e >> f;
	s1 = sqrt((a-c)*(a-c)+(b-d)*(b-d));
	s2 = sqrt((a-e)*(a-e)+(b-f)*(b-f));
	s3 = sqrt((c-e)*(c-e)+(d-f)*(d-f));
	printf("%.2lf\n",s1+s2+s3);
	return 0;
}