#include <bits/stdc++.h> using namespace std; #define int long long int a[300005], b[300005]; int n; bool check(int mid) { int i = 0; int j = n - 1; int cnt = 0; while ((i < n) && (j >= 0)) { if (abs(a[i] - b[j]) >= mid) { i++; j--; cnt++; } else { j--; } } return cnt == n; } signed main() { ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); int T; cin >> T; while (T--) { cin >> n; for (int i = 1; i <= n; i++) cin >> a[i]; for (int i = 1; i <= n; i++) cin >> b[i]; sort(a + 1, a + n + 1); sort(b + 1, b + n + 1); int l = 0; int r = 1e9; int ans = 0; while (l <= r) { int mid = (l + r) / 2; if (check(mid)) { ans = mid; l = mid + 1; } else { r = mid - 1; } } cout << ans << endl; } return 0; }