#include<cstdio>
#include<cmath>
using namespace std;
double x1,y1,x2,y2,x3,y3;
double f()
{
	return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))+sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3))+sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
}
int main()
{
	scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
	printf("%.2lf",f());
	return 0;
}

aaaaaaa-----