#include <bits/stdc++.h>
using namespace std;
double sjxmj(int x1,int y1,int x2,int y2,int x3,int y3);
int main(){
	int x1,y1,x2,y2,x3,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	cout<<fixed<<setprecision(2)<<sjxmj(x1,y1,x2,y2,x3,y3)<<endl;
	return 0;
}

double sjxmj(int x1,int y1,int x2,int y2,int x3,int y3){
	double c=0;
	c+=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
	c+=sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
	c+=sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
	return c;
}