#include <cstdio>
#include <vector>
#include <algorithm>
int T, n, a[3][200010], id[3][200010];
std::vector <int> e[1600010];
int dfn[1600010], low[1600010], tm, Tm, stk[1600010], tp, col[1600010], cnt;
void tarjan(int u) {
	dfn[u] = low[u] = ++tm, stk[++tp] = u;
	for (int v: e[u]) {
		if (dfn[v]) dfn[v] > Tm && low[u] > dfn[v]? low[u] = dfn[v]: 0;
		else tarjan(v), low[u] > low[v]? low[u] = low[v]: 0;
	}
	if (low[u] == dfn[u]) 
		for (++cnt, stk[tp + 1] = -1; stk[tp + 1] != u; --tp) col[stk[tp]] = cnt;
}
int main() {
	scanf("%d", &T);
	while (T--) {
		scanf("%d", &n); n *= 2;
		for (int i = 0; i < n; ++i) for (int k = 0; k < 3; ++k) scanf("%d", &a[k][i]);
		for (int i = 0; i < n * 7; ++i) e[i].clear();
		for (int i = 0; i < 3; ++i) {
			for (int j = 0; j < n; ++j) id[i][j] = j;
			std::sort(id[i], id[i] + n, [i](int x, int y) { return a[i][x] < a[i][y]; });
			int L = (i * 2 + 1) * n, R = L + n;
			for (int j = L + 1; j < R; ++j) e[j].push_back(j - 1), e[j + n - 1].push_back(j + n);
			for (int j = 0; j < n; ++j) e[L + j].push_back(id[i][j] ^ 1), e[R + j].push_back(id[i][j] ^ 1);
		}
		int L = 0, R = 1e9;
		while (L <= R) {
			int mid = (L + R) / 2;
			for (int i = 0; i < n; ++i) e[i].clear();
			for (int i = 0; i < 3; ++i) {
				int L = (i * 2 + 1) * n, R = L + n;
				for (int k = 0, r = 0; k < n; ++k) {
					int j = id[i][k];
					while (a[i][id[i][r]] + mid < a[i][j]) ++r;
					if (r) e[j].push_back(L + r - 1);
				}
				for (int k = n - 1, l = n - 1; k >= 0; --k) {
					int j = id[i][k];
					while (a[i][j] + mid < a[i][id[i][l]]) --l;
					if (l != n - 1) e[j].push_back(R + l + 1);
				}
			}
			for (int i = 0; i < n * 7; ++i) dfn[i] = 0; tm = 0;
			for (int i = 0; i < n; ++i) if (!dfn[i]) Tm = tm, tarjan(i);
			int F = 1;
			for (int i = 0; i < n; i += 2) if (col[i] == col[i + 1]) F = 0;
			if (F) R = mid - 1;
			else L = mid + 1;
		}
		printf("%d\n", L);
	}
}