// Author: btjanaka (Bryon Tjanaka)

// Problem: (UVa) 10034

// Title: Freckles

// Link:

// https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem&problem=975

// Idea: Boruvka's Algorithm for MST

// Difficulty: easy

// Tags: graph, mst

#include <bits/stdc++.h>

#define GET(x) scanf("%d", &x)

#define GED(x) scanf("%lf", &x)

using namespace std;

typedef long long ll;

typedef pair<int, int> ii;

typedef vector<int> vi;

using Edge = pair<pair<int, int>, double>;

struct UnionFind {

vector<int> p, rank;

UnionFind(int n) : p(n), rank(n, 0) { iota(p.begin(), p.end(), 0); }

int find(int i) { return p[i] == i ? i : (p[i] = find(p[i])); }

bool same(int i, int j) { return find(i) == find(j); }

bool join(int i, int j) {

if (same(i, j)) return false;

int x = find(i), y = find(j);

if (rank[x] > rank[y]) {

p[y] = x;

} else {

p[x] = y;

if (rank[x] == rank[y]) {

++rank[y];

}

}

return true;

}

};

double boruvka(int n, const vector<Edge>& edges) {

UnionFind uf(n);

double cost = 0.0;

int selected = 0;

for (int i = 1; selected < n - 1 && i < n; i <<= 1) {

// select edges to add

vector<Edge> closest(n, {{-1, -1}, -1.0});

for (const Edge& e : edges) {

int u, v;

pair<int, int> nodes;

double d;

tie(nodes, d) = e;

tie(u, v) = nodes;

int x = uf.find(u);

int y = uf.find(v);

if (x == y) continue;

// if we compare between nodes instead of parent clusters, we may end up

// adding multiple edges from one cluster to another (e.g. multiple nodes

// in one cluster could connect to the other cluster)

if (closest[x].second == -1.0 || d < closest[x].second) closest[x] = e;

if (closest[y].second == -1.0 || d < closest[y].second) closest[y] = e;

}

// add in edges

for (const Edge& e : closest) {

int u, v;

pair<int, int> nodes;

double d;

tie(nodes, d) = e;

tie(u, v) = nodes;

if (d == -1.0) continue;

if (uf.join(u, v)) {

++selected;

cost += d;

// printf("%d -%.2lf-> %d\n", u, d, v); // debugging

}

}

}

return cost;

}

int main() {

int ca;

GET(ca);

while (ca--) {

int n;

GET(n);

vector<pair<double, double>> pts;

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

double x, y;

GED(x);

GED(y);

pts.push_back({x, y});

}

vector<Edge> edges;

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

for (int j = i + 1; j < n; ++j) {

double dx = pts[i].first - pts[j].first;

double dy = pts[i].second - pts[j].second;

double d = sqrt(dx * dx + dy * dy);

edges.push_back({{i, j}, d});

}

}

printf("%.2lf\n", boruvka(n, edges));

if (ca) printf("\n");

}

return 0;

}