#include<bits/stdc++.h>
using namespace std;
int n;
bool vis[20];
double ans = 1e10;
double x[20], y[20];
void dfs (int num, int k, double sum) {
	if (sum >= ans) return;
	if (k - 1 == n) {
		ans = min(ans, sum);
		return;
	}
	for (int i = 1; i <= n; i++) {
		if (vis[i]) continue;
		vis[i] = true;
		dfs(i, k + 1, sum + sqrt((x[num] - x[i]) * (x[num] - x[i]) + (y[num] - y[i]) * (y[num] - y[i])));
		vis[i] = false;
	}
}
int main () {
//	freopen("P1433_10.in","r",stdin);
	scanf("%d", &n);
	for (int i = 1; i <= n; i++) {
		scanf("%lf%lf", &x[i], &y[i]);
	}
	dfs(0, 1, 0.0);
	printf("%.2lf", ans);
	return 0;
}

15
0 0
1 1
1 -1
-1 1
-1 -1
2 2
2 0
2 -2
0 -2
-2 -2
-2 0
-2 2
0 2
1 3
1 4

21.73