#include <stdio.h>
#include <math.h>
double dis(double a,double b,double c,double d)
{
	int l;
	l=sqrt((c-a)*(c-a)+(d-b)*(d-b));
	return (l);

}
int main()
{
	double dis(double a,double b,double c,double d);
	double x1,y1,x2,y2,x3,y3;
	double i;
	scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
	i=dis(x1,y1,x2,y2)+dis(x2,y2,x3,y3)+dis(x1,y1,x3,y3);
	printf("%.2lf",i);
	return 0;

}