#pragma G++ optimize(3,"Ofast","inline")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n;
double x[21], y[21], a[21][21], dp[21][32768];
inline ll read(){
	ll x = 0, m = 1;
	char ch = getchar();
	while(!isdigit(ch)){
		if(ch == '-') m = -1;
		ch = getchar();
	}
	while(isdigit(ch)){
		x = (x << 1) + (x << 3) + (ch ^ 48);
		ch = getchar();
	}
	return x * m;
}
inline void write(ll x){
	if(x < 0){
		putchar('-');
		write(-x);
		return;
	}
	if(x >= 10) write(x / 10);
	putchar(x % 10 + '0');
}
inline double getsum(int u, int v){
	return (double) sqrt((x[u] - x[v]) * (x[u] - x[v]) + (y[u] - y[v]) * (y[u] - y[v]));
}
signed main(){
	cin >> n;
	for(int i = 1; i <= n; ++ i){
		cin >> x[i] >> y[i];
	}
	for(int i = 0; i < n; ++ i){
		for(int j = i + 1; j <= n; ++ j){
			a[i][j] = a[j][i] = getsum(i, j);
		}
	}
	memset(dp, 127, sizeof dp);
	double ans = dp[0][0];
	for(int i = 1; i <= n; ++ i){
		dp[i][1 << (i - 1)] = a[0][i];
	}
	for(int k = 1; k < (1 << n); ++ k){
		for(int i = 1; i <= n; ++ i){
			if(k & (1 << (i - 1)) == 0) continue;
			for(int j = 1; j <= n; ++ j){
				if(i == j || k & (1 << (j - 1)) == 0) continue;
				dp[i][k] = min(dp[i][k], dp[j][k - (1 << (i - 1))] + a[i][j]);
			}
		}
	}
	for(int i = 1; i <= n; ++ i){
		ans = min(ans, dp[i][(1 << n) - 1]);
	}
	printf("%.2lf", ans);
	return 0;
}

WA on#5