// God & me
// Fly ...
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int maxn = 1e6 + 17, inf = 2e9 + 20;

int t, n, x[maxn], y[maxn], q[maxn];
pii xs[maxn], ys[maxn];
bool mark[maxn];
bool check(int d){
	int h = 0, t = 0;
	int lx = 0, rx = n - 2, ly = 0, ry = n - 2;
	q[t++] = 0;
	memset(mark, 0, sizeof mark);
	auto add = [&](int u){
		q[t++] = u;
		mark[u] = 1;
		while(lx <= rx && mark[ xs[rx].second ])
			rx--;
		while(lx <= rx && mark[ xs[lx].second ])
			lx++;
		while(ly <= ry && mark[ ys[ry].second ])
			ry--;
		while(ly <= ry && mark[ ys[ly].second ])
			ly++;
	};
	while(h < t){
		int v = q[h++];
		//cerr << v << '\n';
		while(lx <= rx && xs[rx].first >= (ll) x[v] + d)
			add(xs[rx].second);
		while(ly <= ry && ys[ry].first >= (ll) y[v] + d)
			add(ys[ry].second);
		while(lx <= rx && xs[lx].first <= (ll) x[v] - d)
			add(xs[lx].second);
		while(ly <= ry && ys[ly].first <= (ll) y[v] - d)
			add(ys[ly].second);
	}
	return h == n;
}
void solve(){
	scanf("%d", &n);
	for(int tx, ty, i = 0; i < n; i++){
		//cin >> tx >> ty;
		scanf("%d%d", &tx, &ty);
		x[i] = tx + ty;
		y[i] = tx - ty;
		if(i > 0){
			xs[i - 1] = {x[i], i};
			ys[i - 1] = {y[i], i};
		}
	}
	sort(xs, xs + n - 1);
	sort(ys, ys + n - 1);
	int lo = 0, hi = inf;
	while(hi - lo > 1){
		int mid = ((ll) lo + hi) / 2;
		(check(mid) ? lo : hi) = mid;
	}
	//cout << lo << '\n';
	printf("%d\n", lo);
}
int main(){
	scanf("%d", &t);
	while(t--)
		solve();
	return 0;
}