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