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

int main(void)
{
	int i;
	float x1,x2,x3,sum;
	int a[3];
	int b[3];
	for (i = 0;i < 3;++i)
	{
		scanf("%d %d",&a[i],&b[i]);
	}
		x1 = sqrt((a[0]-a[1])*(a[0]-a[1])+(b[0]-b[1])*(b[0]-b[1]));
		x2 = sqrt((a[0]-a[2])*(a[0]-a[2])+(b[0]-b[2])*(b[0]-b[2]));
		x3 = sqrt((a[1]-a[2])*(a[1]-a[2])+(b[1]-b[2])*(b[1]-b[2]));
		sum = x1 + x2 + x3;
		printf("%.2f\n",sum);
		return 0;
}