#include<bits/stdc++.h>
using namespace std;
int x[105],y[105];
double sum;
double dis(double a,double b,double c,double d){
	double x;
	x=sqrt((c-a)*(c-a)+(d-b)*(d-b));
	return x;
}
int main(){
	for(int i=0;i<3;++i){
		cin>>x[i]>>y[i];
	}
	for(int i=0;i<2;++i)
		for(int j=i;j<2;++j)
			sum+=dis(x[j],y[j],x[j+1],y[j+1]);
	cout<<fixed<<setprecision(2)<<sum;
	return 0;
}