#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int a(double x1,double y1,double x2,double y2){
	return sqrt(abs((x2-x1)*(x2-x1))+abs((y2-y1)*(y2-y1)));
}
int main(){
	double x1,x2,x3,y1,y2,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	double s=a(x1,y1,x2,y2),l=a(x2,y2,x3,y3),h=a(x3,y3,x1,y1);
	printf("%.2f",s+l+h);
	return 0;
}