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#include<bits/stdc++.h>
using namespace std;
double dis(float x1,float y1,float x2,float y2){
	float js=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
	return js;
}
int main(){
	int x1,x2,x3,y1,y2,y3;
	cin>>x1>>y1;
	cin>>x2>>y2;
	cin>>x3>>y3;
	float ans=0,a,b,c;
	a=dis(x1,y1,x2,y2);
	b=dis(x1,y1,x3,y3);
	c=dis(x2,y2,x3,y3);
	ans+=a+b+c;
	 printf("%.2f",ans);
	return 0;
}