#include <bits/stdc++.h> using namespace std; #define int long long int n, a[300005], b[300005]; bool check(int mid) { int i = 0, j = 0, cnt = 0; while (i < n && j < n) { if (abs(a[i] - b[j]) >= mid) { cnt++, i++, j++; } else { j++; } } return cnt == n; } signed main() { ios::sync_with_stdio(0); cin.tie(0); int T; cin >> T; while (T--) { cin >> n; for (int i = 0; i < n; i++) cin >> a[i]; for (int i = 0; i < n; i++) cin >> b[i]; sort(a, a + n); sort(b, b + n); int l = 0, r = 1e9, ans = 0; while (l <= r) { int mid = l + r >> 1; if (check(mid)) { ans = mid; l = mid + 1; } else { r = mid - 1; } } cout << ans << '\n'; } return 0; }