#include <bits/stdc++.h>
using namespace std;
double distance(double x1,double y1,double x2,double y2);
int main(){
	double x1,y1,x2,y2,x3,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	double jl1,jl2,jl3;
	jl1=distance(x1,y1,x2,y2);
	jl1=distance(x2,y2,x3,y3);
	jl1=distance(x3,y3,x1,y1);
	cout<<fixed<<setprecision(2)<<jl1+jl2+jl3;
	return 0;
}
double distance(double x1,double y1,double x2,double y2){
	double disc=sqrt(pow(x1-x2,2)+pow(y1-y2,2));
   return disc;
}