#include <bits/stdc++.h>
using namespace std;


	double  dis(double x1, double y1, double x2, double y2 )
	{
		
		double result,mm,m,nn,n,tm;
		mm=(x1-x2)*(x1-x2)*1.0;
		
		
		nn=(y1-y2)*(y1-y2)*1.0;
		
		tm=mm+nn;
		result=double(sqrt(tm));
		
		return result;
		
	}
	
	int main ()
	{
		double ans[6],x[2],y[2];
		for(int i=0;i<3;i++)
		{
			cin>>x[i]>>y[i];
		}
		
		double  ret=dis(x[0],y[0],x[1],y[1])+dis(x[0],y[0],x[2],y[2])+dis(x[1],y[1],x[2],y[2])
		;
		printf("%.2lf",ret);
		return 0;
	}