func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long MOD = 998244353;   const int MAXN = 1000100;   long long mpow(long long b, int e) {     if (e == 0) return 1;     long long v = mpow(b, e / 2);     v = (v * v) % MOD;     if (e & 1) v = (v * b) % MOD;     return v;   }   long long inv(long long b) { return mpow(b % MOD, MOD - 2); }   int N;   vector<int> v[MAXN];   int ct[MAXN];   int main() {     ios_base::sync_with_stdio(0);     cin >> N;     for (int i = 0; i < N; i++) {       int K;       cin >> K;       for (int j = 0; j < K; j++) {         int x;         cin >> x;         v[i].push_back(x);         ct[x]++;       }     }     long long res = 0;     for (int i = 0; i < N; i++) {       for (int cv : v[i]) {         long long prob = (inv(v[i].size() * (long long)N)) % MOD;         prob = (prob * ct[cv]) % MOD;         prob = (prob * inv(N)) % MOD;         res = (res + prob) % MOD;       }     }     cout << res <<   n ;   }   