#include <bits/stdc++.h>
using namespace std;
const long long inf = 1000 * 1000 * 1000;
const long long inf64 = 1ll * inf * inf;
const long long mod = 1e9 + 7;
mt19937 rng(0);
long long binpow(long long a, long long p, long long mod = 998244353) {
  if (p == 0) return 1;
  if (p % 2 == 0) {
    long long t = binpow(a, p / 2);
    return t * t % mod;
  } else {
    return binpow(a, p - 1) * a % mod;
  }
}
long long invert(long long x) { return binpow(x, 998244351); }
pair<long long, long long> add(pair<long long, long long> a,
                               pair<long long, long long> b) {
  pair<long long, long long> ans;
  ans.first = a.first * b.second + b.first * a.second;
  ans.second = a.second * b.second;
  ans.first %= 998244353;
  ans.second %= 998244353;
  return ans;
}
pair<long long, long long> multi(pair<long long, long long> a,
                                 pair<long long, long long> b) {
  return {a.first * b.first % 998244353, a.second * b.second % 998244353};
}
void run() {
  long long n;
  cin >> n;
  vector<vector<long long>> a(n);
  vector<vector<long long>> poses(1e6 + 10);
  for (long long i = 0; i < n; i++) {
    long long k;
    cin >> k;
    a[i].resize(k);
    for (long long j = 0; j < k; j++) {
      cin >> a[i][j];
      poses[a[i][j]].push_back(i);
    }
  }
  pair<long long, long long> ans = {0, 1};
  for (long long i = 0; i < n; ++i) {
    pair<long long, long long> t = {1, n};
    for (long long k = 0; k < a[i].size(); ++k) {
      pair<long long, long long> r = {1, a[i].size()};
      pair<long long, long long> e = {poses[a[i][k]].size(), n};
      ans = add(ans, multi(multi(t, r), e));
    }
  }
  cout << ans.first * invert(ans.second) % 998244353;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  for (long long i = 0; i < t; i++) {
    run();
  }
  return 0;
}
