#include <stdio.h>
#include <math.h>

double distance(double ,double ,double ,double);//求两个点之间的距离

int main(){
    double a1,a2,a3,b1,b2,b3;
    scanf("%lf %lf",&a1,&b1);
    scanf("%lf %lf",&a2,&b2);
    scanf("%lf %lf",&a3,&b3);
    
    double a = distance(a1,b1,a2,b2);
    double b = distance(a2,b2,a3,b3);
    double c = distance(a1,b1,a3,b3);

    printf("%.2lf\n",a+b+c);
    
    return 0;
}

double distance(double a1,double b1,double a2,double b2){
    double dis;
    dis = sqrt(abs(a2-a1)*abs(a2-a1)+abs(b2-b1)*abs(b2-b1));
    return dis;
}