#include <iostream>
#include <cmath>
#include <cstdio>
using namespace std;
double sq(double x)
{
    return x*x;
}
double dis(double x1,double y1,double x2,double y2)
{return sqrt(sq(x2-x1)+sq(y2-y1));}

int main(){
double c=0,x1,y1,x2,y2,x3,y3;
cin>>x1>>y1>>x2>>y2>>y3>>y3;
c+=dis(x1,y1,x2,y2);
c+=dis(x2,y2,x3,y3);
c+=dis(x1,y1,x3,y3);
printf("%.2f",c);
return 0;
}