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

float jishuan(int a,int b,int c,int d){//x1 x2 y1 y2
    return sqrt(fabs((a-b)*(a-b)+(c-d)*(c-d)));
}

int main() {
    float x1,x2,x3,y1,y2,y3;
    scanf("%f %f",&x1,&y1);
    scanf("%f %f",&x2,&y2);
    scanf("%f %f",&x3,&y3);
    printf("%.2f",jishuan(x1,x2,y1,y2)+jishuan(x2,x3,y2,y3)+jishuan(x1,x3,y1,y3));
    return 0;
}

//在第五个节点的时候,我的计算机输出是486.21,但是洛谷上面返回的值是489.20