/*
 * main.cpp
 *
 *  Created on: May 24, 2016
 *      Author: alexei
 */

#include <cstdio>
#include <algorithm>
#include <vector>
#include <limits>
#include <set>

#define NMAX 200020
#define MAX_T 20
#define MAX_N 200000
#define MAX_X 1000000000

class Point {

public:

    int x, y;
    int idx;

    Point(int x, int y): x(x), y(y) {
    }

};

// Manhattan distance
inline int distance(Point& p1, Point& p2) {
    return std::abs(p1.x - p2.x) + std::abs(p1.y - p2.y);
}

int min_dist[NMAX];

long long brute_prim(std::vector<Point>& points) {

    int N = points.size();
    long long mst_cost = 0;

    // boot-up MST from point 0
    min_dist[0] = std::numeric_limits<int>::max();
    for (int i = 1; i < N; ++i) {
        min_dist[i] = distance(points[i], points[0]);
    }

    for (int i = 1; i < N; ++i) {

        // search for the nearest point in plane
        int nearest_neigh_dist = std::numeric_limits<int>::max();
        int nearest_neigh_idx  = -1;

        for (int j = 0; j < N; ++j) {
            if (min_dist[j] < nearest_neigh_dist) {
                nearest_neigh_idx = j;
                nearest_neigh_dist = min_dist[j];
            }
        }

        // update relative distance to MST
        for (int j = 0; j < N; ++j) {
            if (min_dist[j] != std::numeric_limits<int>::max()) {
                int new_dist = distance(points[j], points[nearest_neigh_idx]);
                min_dist[j] = std::min(min_dist[j], new_dist);
            }
        }

        // append point to MST
        mst_cost += (long long) nearest_neigh_dist;
        min_dist[nearest_neigh_idx] = std::numeric_limits<int>::max();
    }

    return mst_cost;
}

int main () {

    if (freopen("metrou4.in", "r", stdin) == NULL) {
        return 1;
    }
    
    if (freopen("metrou4.out", "w", stdout) == NULL) {
        return 1;
    }

    std::vector<Point> points;

    int T, ret;
    ret = scanf("%d\n", &T);

    if (ret != 1) {
        fprintf(stderr,"Failure parsing input file!\n");
        return 1;
    }

    while (T--) {

        int N;
        ret = scanf("%d\n", &N);

        points.clear();
        for (int i = 0; i < N; ++i) {
            int X, Y;
            ret = scanf("%d%d\n", &X, &Y);
            points.push_back(Point(X, Y));
        }

        long long brute_cost = brute_prim(points);
        printf("%lld\n", brute_cost);
    }

    return 0;
}