#include<bits/stdc++.h>
using namespace std;
int main(){
    double x1,y1,x2,y2,x3,y3;
    cin>>x1>>y1>>x2>>y2>>x3>>y3;
    double s=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))+sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2))+sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
    printf("%.2lf",s);
    return 0;
}