#include<iostream>
#include<math.h>
using namespace std;
int main()
{
	int x1, x2, x3, y1, y2, y3;
	scanf("%d %d", &x1, &y1);
	scanf("%d %d", &x2, &y2);
	scanf("%d %d", &x3, &y3);
	double dis1, dis2, dis3;
	dis1 = sqrt(abs(x1 - x2) * abs(x1 - x2) + abs(y1 - y2) * abs(y1 - y2));
	dis2 = sqrt(abs(x3 - x2) * abs(x3 - x2) + abs(y3 - y2) * abs(y3 - y2));
	dis3 = sqrt(abs(x1 - x3) * abs(x1 - x3) + abs(y1 - y3) * abs(y1 - y3));
	double sum = dis1 + dis2 + dis3;
	printf("%.2lf",sum);
	return 0;
}