#include<stdio.h>
#include<iostream>
#include<math.h>
float mathf(float,float,float,float );
int main()
{
    float a1,a2,b1,b2,c1,c2,A=0,B=0,C=0,ZC=0;
    scanf("%f%f",&a1,&a2);
    scanf("%f%f",&b1,&b2);
    scanf("%f%f",&c1,&c2);
    A=mathf(a1,a2,b1,b2);
    B=mathf(b1,b2,c1,c2);
    C=mathf(c1,c2,a1,a2);
    ZC=A+B+C;
    printf("%.2f",ZC);
    return 0;
}
float mathf(float x1,float x2,float y1,float y2 )
{
    float dis=0,x=0,y=0;
    x=x1-x2;
    y=y1-y2;
    dis=sqrt(x*x+y*y);
    return dis;
}