#include<bits/stdc++.h>
using namespace std;
//变量定义区
double x,y,xx,yy,xxx,yyy,ans;
//函数定义区
double qda(double x1,double x2,double y1,double y2){
	return sqrt(abs((x1 - x2) * (x1 - x2)) + abs((y1 - y2) * (y1 - y2)));

}
//主函数の区
int main(){
	cin>>x>>y>>xx>>yy>>xxx>>yyy;
	double a1=qda(x,y,xx,yy);
	double a2=qda(xx,yy,xxx,yyy);
	double a3=qda(x,y,xxx,yyy);
	ans=a1+a2+a3;
	printf("%.2lf\n",ans);
	return 0;
}