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

struct zc {
	int x;
	int y;
}a[4];

int cd(zc a, zc b) {
	double a1 = pow((b.x - a.x), 2.0);
	double a2 = pow((b.y - a.y), 2.0);
	double zc = pow((a1 + a2), 1 / 2);
	return zc;
}

int main() {
	for (int i = 1; i <= 3; i++) {
		cin >> a[i].x >> a[i].y;
	}
	double zzc = cd(a[1], a[2]) + cd(a[1], a[3]) + cd(a[2], a[3]);
	printf("%0.2lf", zzc);
	return 0;
}

按公式写的