#include <bits/stdc++.h>

#define WHITE 10
#define BLACK 9


using namespace std;



class DisjointSet {
public:
    DisjointSet(int num_nodes);
    int parent(int element);
    void do_union(int element_a, int element_b);
private:
    std::vector<int> parent_;
    std::vector<int> rank_;
};

DisjointSet::DisjointSet(int num_nodes):parent_(num_nodes),rank_(num_nodes, 0){
    for(int i=0; i<num_nodes; ++i) parent_[i] = i;
}

int DisjointSet::parent(int element){
    if(parent_[element] == element) return element;
    //1)path compression
    return (parent_[element] = parent(parent_[element]));
}

void DisjointSet::do_union(int a, int b){
    if(parent_[a] == parent_[b]) return;
    int fa = parent(a), fb = parent(b);
    //2)union by rank
    if(rank_[fa] < rank_[fb]) {
        parent_[fa] = fb;
    } else {
        parent_[fb] = fa;
        if(rank_[fa] == rank_[fb])
            rank_[fa]++;
    }
}


typedef pair< int, int > pi;

int main(){

    int casos, n;
    vector<pair<double,double>> pintas_coord;
    vector<pair<double,pi>> arestas;   //arestas grafo original
    vector<pair<double,pi>> min_tree;  //arestas arvore minima



    double x,y, x2, y2;


    scanf("%d", &casos);

    while(casos--){
        pintas_coord.clear();
        arestas.clear();
        min_tree.clear();
        arestas.reserve(n*n);
        min_tree.reserve(n*n);

        scanf("%d", &n);
        for(int i=0; i<n;i++){
            scanf("%lf %lf", &x, &y);
            pintas_coord.push_back(make_pair(x,y));
        }


        //criando arestas
        for(int i=0; i<n; i++){
            for(int j=i+1; j<n; j++){
                x=pintas_coord[i].first; y=pintas_coord[i].second;
                x2=pintas_coord[j].first; y2=pintas_coord[j].second;

                double peso = sqrt(pow(x - x2, 2) + pow(y - y2, 2));
                arestas.push_back( make_pair( peso, make_pair(i, j)) );
            }
        }

        /**********************KRUSKAL*****************/
        double total_lenght=0;

        sort(arestas.begin(), arestas.end());
        DisjointSet ds(n);

        for(auto &aresta: arestas){
            int u = aresta.second.first;
            int v = aresta.second.second;

            int set_u = ds.parent(u);
            int set_v = ds.parent(v);

            if(set_u != set_v){
                min_tree.push_back( make_pair(aresta.first, make_pair(u,v)) );
                total_lenght += aresta.first;
                ds.do_union(set_u, set_v);
            }

        }

        printf("%.2lf", total_lenght);
        if(casos>0)
            printf("\n");


    }


}