#include <stdio.h>

#include <stdlib.h>

#include <math.h>

#define maxn 15

#define INF (0x7fffffff*1.0)

double dp[1<<maxn][maxn];

double x[maxn], y[maxn];

double square(double a) {

return a*a;

}

double dist(double x1, double y1, double x2, double y2) {

return sqrt(square(x1 - x2) + square(y1 - y2));

}

double dist_index(int i, int j) {

return dist(x[i], y[i], x[j], y[j]);

}

double min(double a, double b) {

return a < b ? a : b;

}

int main() {

int n;

scanf("%d", &n);

for (int i = 0; i < n; i++) {

scanf("%lf %lf", &x[i], &y[i]);

dp[1 << i][i] = dist(x[i], y[i], 0, 0); //Init

}

int state, pre, count;

for (state = 3; state < 1 << n; state++) {

count = 0;

for (int i = 0; i < n; i++)

if (state & (1 << i))

count++;

if (count <= 1) continue; //二进制位只有一个1的 在初始化时已经计算过

for (int i = 0; i < n; i++) {

if (state & (1 << i)) {

dp[state][i] = INF; //Init

pre = state ^ (1 << i); //state可以从pre转来

for (int j = 0; j < n; j++)

if (pre & (1 << j)) {

dp[state][i] = min(

dp[state][i],

dp[pre][j] + dist_index(i, j)

);

}

}

}

}

double ans = INF;

for (int i = 0; i < n; i++) {

ans = min(ans, dp[(1 << n) - 1][i]);

}

printf("%0.2lf\n", ans);

exit(0);

}