#include<bits/stdc++.h>
using namespace std;
double d(double x1, double y1, double x2, double y2)
{
	return sqrt(abs((x1 - x2) * (x1 - x2)) + abs((y1 - y2) * (y1 - y2)));
}
int main(){
	int x1,y1,x2,y2,x3,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;

	double d1 = d(x1, y1, x2, y2) ;
	double d2 =d(x2,y2,x3,y3);
	double d3=d(x1,y1,x3,y3);
	double c = d1 + d2 + d3;
	cout<<fixed<<setprecision(2)<<c;	
}