#include<bits/stdc++.h>
using namespace std;
double dis(double x1, double y1, double x2, double y2)
{
	return sqrt((x1-x2)*(x1-x2))+((y1-y2)*(y1-y2));
}
int main()
{
	double a,b,c,d,e,f,sum;
	cin>>a>>b>>c>>d>>e>>f;
	double dis1=dis(a,b,c,d),dis2=dis(c,d,e,f),dis3=dis(e,f,a,b);
	sum=dis1+dis2+dis3;
	cout<<sum;
	return 0;
}