#include <bits/stdc++.h>
#pragma GCC optimize("O2")
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
const long long N = 1e6 + 2;
long long fre[N];
const long long mod = 998244353;
long long power(long long a, long long n) {
  long long res = 1;
  while (n) {
    if (n & 1) res *= a, res %= mod;
    a *= a;
    a %= mod;
    n /= 2;
  }
  return res;
}
void solve() {
  long long n;
  cin >> n;
  vector<long long> v[n];
  for (long long i = 0; i < n; ++i) {
    long long k;
    cin >> k;
    for (long long j = 0; j < k; ++j) {
      long long gift;
      cin >> gift;
      v[i].push_back(gift);
      fre[gift]++;
    }
  }
  long long ans = 0;
  for (long long i = 0; i < n; ++i) {
    const long long den = n * n * v[i].size();
    const long long inv = power(den % mod, mod - 2);
    for (long long &gift : v[i]) {
      long long val = fre[gift];
      ans += val * inv;
      ans %= mod;
    }
  }
  cout << ans << '\n';
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long t = 1;
  for (long long i = 1; i <= t; ++i) solve();
}
