#include<bits/stdc++.h>
using namespace std;
double dis(double x1,double x2,double y1,double y2)
{
	return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
int main()
{
   	double x1,x2,x3,y1,y2,y3,c=0;
   	cin>>x1>>y1>>x2>>y2>>x3>>y3;
    c+=dis(x1,y1,x2,y2)+dis(x1,y1,x3,y3)+dis(x3,y3,x2,y2);
    printf("%.2lf",c);

}