#include <cstdio>
#include <vector>
#include <algorithm>
int T, n, a[3][200010], id[3][200010], Lp[3][200010], Rp[3][200010];
int vis[200010], stk[200010], tp, col[200010], F;
int fr[3], tl[3];
void dfs(int u) {
	vis[u] = 1;
	for (int i = 0; i < 3; ++i) if (fr[i] < tl[i]) {
		while (fr[i] < Lp[i][u]) {
			int u = id[i][fr[i]++] ^ 1;
			if (!vis[u]) dfs(u);
		}
		while (tl[i] > Rp[i][u]) {
			int u = id[i][tl[i]--] ^ 1;
			if (!vis[u]) dfs(u);
		}
	}
	stk[++tp] = u;
}
void sfd(int u) {
	col[u] = F;
	if (col[u ^ 1] == F || F == -1) return F = -1, void();
	for (int i = 0; i < 3; ++i) if (fr[i] < tl[i]) {
		while (fr[i] < Lp[i][u ^ 1]) {
			int u = id[i][fr[i]++];
			if (!col[u]) sfd(u);
		}
		while (tl[i] > Rp[i][u ^ 1]) {
			int u = id[i][tl[i]--];
			if (!col[u]) sfd(u);
		}
	}
}
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 < 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 = 0, R = 1e9;
		while (L <= R) {
			int mid = (L + R) / 2;
			for (int i = 0; i < 3; ++i) {
				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;
					Lp[i][j] = r;
				}
				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;
					Rp[i][j] = l;
				}
			}
			for (int i = 0; i < 3; ++i) fr[i] = 0, tl[i] = n - 1;
			for (int i = 0; i < n; ++i) vis[i] = col[i] = 0;
			for (int i = 0; i < n; ++i) if (!vis[i]) dfs(i);
			for (int i = 0; i < 3; ++i) fr[i] = 0, tl[i] = n - 1; F = tp = 0;
			for (int i = n; i && ~F; --i) if (!col[stk[i]]) ++F, sfd(stk[i]);
			if (~F) R = mid - 1;
			else L = mid + 1;
		}
		printf("%d\n", L);
	}
}