#include <iostream>
#include <cmath>
#include <map>
#include <queue>
#include <set>
using namespace std;
typedef pair<double, double> point;
//Gives a vector of adjacent nodes to a point
typedef map< point, vector<point> > graph;
//Edge of length "first" that arrives to point "second"
typedef pair<double, point> edge;
double euclidean(const point &a, const point &b){ return hypot(a.first-b.first, a.second-b.second);}
int main(){
int casos;
cin >> casos;
while (casos--){
graph g;
int n;
cin >> n;
while (n--){
double x,y;
cin >> x >> y;
point p(x,y);
if (g.count(p) == 0){ //Si no está todavía
vector<point> v;
g[p] = v;
for (graph::iterator i = g.begin(); i != g.end(); ++i){
if ((*i).first != p){
(*i).second.push_back(p);
g[p].push_back((*i).first);
}
}
}
}
set<point> visited;
priority_queue<edge, vector<edge>, greater<edge> > q;
//Each edge in q has got a length "first" and a point "second".
//It means I can reach point "second" which is "first" meters away.
//q has the closest reachable node on top (I may have already visited it!)
q.push(edge(0.0, (*g.begin()).first));
double totalDistance = 0.0;
while (!q.empty()){
edge nearest = q.top();
q.pop();
point actualNode = nearest.second;
if (visited.count(actualNode) == 1) continue; //Ya habia visitado este
totalDistance += nearest.first;
visited.insert(actualNode);
vector<point> neighbors = g[actualNode];
for (int i=0; i<neighbors.size(); ++i){
point t = neighbors[i];
double dist = euclidean(actualNode, t);
q.push(edge(dist, t));
}
}
printf("%.2f\n", totalDistance);
if (casos > 0) cout << endl; //Endl between cases
}
}
