#include<bits/stdc++.h>
using namespace std;
int a,m,j,h,g;
double x1,y1,x2,y2,x3,y3;
double xy (double x1,double y1,double x2,double y2)
{
	return sqrt(pow(abs(x1-x2),2)+pow(abs(y1-y2),2));	
}
int main()
{
cin>>x1>>y1;
cin>>x2>>y2;
cin>>x3>>y3;
printf ("%2f", (xy (x1,y1,x2,y2)+xy (x3,y3,x2,y2)+xy (x1,y1,x3,y3)))
 
    return 0;
}