#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

int n, a[20];
bool flag[20];
double x[20], y[20], ans = 1e9;

double cal(double x, double y, double a, double b)
{
	return sqrt((x - a) * (x - a) + (y - b) * (y - b));
}

void dfs(int step, int last, double sum)
{
	if (sum >= ans) return;
	if (step > n)
	{
		ans = min(sum,ans);
		return;
	}
	for (int i = 1; i <= n; i++)
	{
		if (flag[i]) continue;
		flag[i] = true; 
		dfs(step + 1, i, sum + cal(x[i],y[i],x[last],y[last]));
		flag[i] = false;
	}
}

int main()
{
	scanf("%d", &n);
	for(int i = 1; i <= n; i++) scanf("%lf%lf", &x[i], &y[i]);
	dfs(1, 0, 0);
	cout << fixed << setprecision(2) << ans << endl;
	return 0;
}

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求大佬们给深搜优化我是不会说我不会状压的