func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long p = 998244353;   long long n, ans, a[1000010], c[1000010], cnt[1000010];   long long ksm(long long x, long long y) {     long long xlh = 1;     while (y) {       if (y & 1) xlh = xlh * x % p;       x = x * x % p;       y /= 2;     }     return xlh;   }   int main() {     long long i, j, x;     scanf( %lld , &n);     for (i = 1; i <= n; i++) {       scanf( %lld , &a[i]);       for (j = 1; j <= a[i]; j++) {         scanf( %lld , &x);         cnt[x]++;         c[x] = (c[x] + ksm(a[i], p - 2) * ksm(n, p - 2) % p) % p;       }     }     for (i = 1; i <= 1000000; i++)       if (cnt[i]) {         ans = (ans + c[i] * cnt[i] % p * ksm(n, p - 2) % p) % p;       }     printf( %lld , ans);   }   