#include<bits/stdc++.h>
using namespace std;
double jl(double x1,double y1,double x2,double y2)
{
	return sqrt(pow((x1-x2),2)+pow((y1-y2),2));
}
int main()
{
	int x[10],y[10];
    for(int i=1;i<4;i++)
        cin>>x[i]>>y[i];
	double a,b,c;
	a=jl(x[1],y[1],x[2],y[2]);
	b=jl(x[1],y[1],x[3],y[3]);
	c=jl(x[2],y[2],x[3],y[3]);
	cout<<fixed<<setprecision(2)<<a+b+c;
	return 0;
}

include<bits/stdc++.h> using namespace std; int jv(double a,double b,double c,double d) {

if(abs(a)<100||abs(a)==100&&abs(b)<100||abs(b)==100&&abs(c)<100||abs(c)==100&&abs(d)<100||abs(d)==100)
{
   
	return  sqrt(((a-c)*(a-c)*1.00+(b-d)*(b-d)*1.00)/0.1/10);
}

} int main() { double a,b,c,d,e,f,zhou; cin>>a>>b>>c>>d>>e>>f; zhou=(jv(a,b,c,d)+jv(a,b,e,f)+jv(c,d,e,f))*1.00; cout<<fixed<<setprecision(2)<<zhou; }