#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
long long max(long long a, long long b) {
  if (a > b)
    return a;
  else
    return b;
}
long long min(long long a, long long b) {
  if (a > b)
    return b;
  else
    return a;
}
long long gcd(long long a, long long b) { return (b == 0) ? a : gcd(b, a % b); }
inline long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
inline long long normalize(long long x, long long mod) {
  x %= mod;
  if (x < 0) x += mod;
  return x;
}
long long dx[4] = {0, 1, 0, -1};
long long dy[4] = {1, 0, -1, 0};
string abc = "abcdefghijklmnopqrstuvwxyz";
const double PI = acosl(-1);
const long long mod = 1000 * 1000 * 1000 + 7;
const long long inf = 1e18 + 5;
inline long long add(long long a, long long b, long long p = mod) {
  long long c = a + b;
  if (c >= p) c -= p;
  return c;
}
inline long long sub(long long a, long long b, long long p = mod) {
  long long c = a - b;
  if (c < 0) c += p;
  return c;
}
inline long long mul(long long a, long long b, long long p = mod) {
  return (a * 1LL * b) % p;
}
long long floor1(long long n, long long k) {
  if (n % k == 0 || n >= 0) return n / k;
  return (n / k) - 1;
}
long long ceil1(long long n, long long k) { return floor1(n + k - 1, k); }
long long powm(long long a, long long b) {
  long long res = 1;
  while (b) {
    if (b & 1) res = (res * a) % mod;
    a = (a * a) % mod;
    b >>= 1;
  }
  return res;
}
const long long N = 2e5 + 5;
long long n, m;
vector<long long> g[N];
vector<long long> topo;
long long ans = 0;
bool toposort(long long n) {
  topo.clear();
  queue<pair<long long, long long>> q;
  vector<long long> indeg(n + 1, 0);
  vector<long long> dp(n + 1, 0);
  for (long long i = 1; i <= n; i++)
    for (auto &it : g[i]) indeg[it]++;
  for (long long i = 1; i <= n; i++) {
    if (!indeg[i]) q.push({i, 1});
  }
  while (!q.empty()) {
    pair<long long, long long> x = q.front();
    long long u = x.first;
    long long lvl = x.second;
    ans = max(ans, lvl);
    q.pop();
    topo.push_back(u);
    for (auto &v : g[u]) {
      if (v > u) {
        dp[v] = max(dp[v], lvl);
      } else {
        dp[v] = max(dp[v], lvl + 1);
      }
      indeg[v]--;
      if (!indeg[v]) q.push({v, dp[v]});
    }
  }
  return (topo.size() == n);
}
void solve() {
  cin >> n;
  for (long long i = (1); i < (n + 1); ++i) g[i].clear();
  for (long long i = (1); i < (n + 1); ++i) {
    long long k;
    cin >> k;
    for (long long j = (0); j < (k); ++j) {
      long long u;
      cin >> u;
      g[u].push_back(i);
    }
  }
  ans = 0;
  if (toposort(n)) {
    cout << ans << "\n";
  } else
    cout << -1 << "\n";
}
signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout << fixed << setprecision(10);
  long long t = 1;
  cin >> t;
  for (long long i = (1); i < (t + 1); ++i) {
    solve();
  }
  return 0;
}
