#include <bits/stdc++.h>
using namespace std;

double dis(double a1, double b1, double a2, double b2) {
	int tmp;
	tmp = sqrt(pow((a1 - a2), 2) + pow((b1 - b2), 2));
	return tmp;
}

int main() {
	double a1, a2, a3, b1, b2, b3, tmp = 0;
	cin >> a1 >> b1 >> a2 >> b2 >> a3 >> b3;
	tmp += dis(a1, b1, a2, b2);
	tmp += dis(a1, b1, a3, b3);
	tmp += dis(a2, b2, a3, b3);
	printf("%.2f", tmp);
	return 0;
}