#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
//#define int long long
using namespace std;
inline int read()
{
	char c=getchar();int x=0;bool f=0;
	for(;!isdigit(c);c=getchar())f^=!(c^45);
	for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
	if(f)x=-x;return x;
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 800005
#define inf 0x3f3f3f3f

const double eps=1e-10,pi=3.14159265358979323846;
struct P{
	double x,y;
	P(double x=0,double y=0):x(x),y(y){}
	P&operator +=(P o){return x+=o.x,y+=o.y,*this;}
	P&operator -=(P o){return x-=o.x,y-=o.y,*this;}
	P&operator *=(double o){return x*=o,y*=o,*this;}
	P&operator /=(double o){return x/=o,y/=o,*this;}
	friend P operator +(P a,P b){return a+=b;}
	friend P operator -(P a,P b){return a-=b;}
	friend P operator *(P a,double b){return a*=b;}
	friend P operator /(P a,double b){return a/=b;}
	friend bool operator <(P a,P b){return fabs(a.x-b.x)<eps?a.y<b.y:a.x<b.x;}
	friend double operator *(P a,P b){return a.x*b.x+a.y*b.y;} // dot
	friend double operator %(P a,P b){return a.x*b.y-a.y*b.x;} // cross
	inline void spin(double o){double s=sin(o),c=cos(o),xx=x*c-y*s,yy=x*s-y*c;x=xx,y=yy;}
	inline double ang(){return atan2(y,x);}
	inline double l(){return sqrt((*this)*(*this));}
	void in(){cin>>x>>y;}
};
inline double d(P a,P b){return (a-b).l();}

P a,b,c;

signed main()
{
	a.in(),b.in(),c.in();
	double res=d(a,c)+2*d(b,c);
	printf("%.12lf\n",res);
	return 0;
}