#include <bits/stdc++.h>
double n(double a , double b , double c , double d){
    double x = pow (c - a , 2);
    double y = pow (d - b , 2);
    double dis = sqrt (x + y);
    return dis;
}
using namespace std;
int main(){
    double x1 , y1 , x2 , y2 , x3 , y3;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    double a = n (x1 , y1 , x2 , y2);
    double b = n (x2 , y2 , x3 , y3);
    double c = n (x3 , y3 , x1 , y1);
    printf("%.2lf",a + b + c);
    return 0;
}