#include<bits/stdc++.h>
using namespace std;
int j(double y,double y2,double x2,double x1){
    return sqrt((x1-x2)*(x1-x2)+(y-y2)*(y-y2));
}

double x1,x2,x3,y,y2,y3,c;
int main(){
    cin>>x1>>y>>x2>>y2>>x3>>y3;  
    c+=j(x1,x2,y,y2)+j(x2,x3,y2,y3)+j(x1,x3,y,y3);
    cout<<fixed<<setprecision(2)<<c;
}