#include<bits/stdc++.h>
using namespace std;
long double kill(long double x1,long double x2,long double y1,long double y2)
{
	return sqrt(abs(x1-x2)*abs(x1-x2)+abs(y1-y2)*abs(y1-y2));
}
int main()
{
    long double x1,y1,x2,y2,x3,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	cout<<fixed<<setprecision(2)<<kill(x1, y1, x2, y2)+kill(x2, y2, x3, y3)+kill(x3, y3, x1, y1);
	return 0;
}