func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 1000005;   const long long mod = 1e9 + 7;   const int N = 1e6;   vector<int> rec[maxn];   long long fac[maxn], ans;   int n, m;   int ord[maxn], bit;   bool comp(int a, int b) { return rec[a][bit] < rec[b][bit]; }   void mysort(int l, int r, int j) {     if (l == r) return;     bit = j;     sort(ord + l, ord + r + 1, comp);     int p = l;     while (p <= r && rec[ord[p]][j] == -1) ++p;     int cnt = 1;     for (int i = l + 1; i < p; i++)       if (rec[ord[i]][j - 1] == rec[ord[i - 1]][j - 1])         ++cnt;       else {         (ans *= fac[cnt]) %= mod;         cnt = 1;       }     (ans *= fac[cnt]) %= mod;     int t = p;     while (t <= r) {       p = t;       while (p <= r && rec[ord[p]][j] == rec[ord[t]][j]) ++p;       mysort(t, p - 1, j + 1);       t = p;     }   }   int main() {     fac[0] = 1ll;     for (int i = 1; i <= N; i++) fac[i] = fac[i - 1] * i % mod;     scanf( %d %d , &n, &m);     for (int i = 1; i <= m; i++) rec[i].push_back(0);     for (int g, i = 1; i <= n; i++) {       scanf( %d , &g);       for (int v, j = 1; j <= g; j++) scanf( %d , &v), rec[v].push_back(i);     }     for (int i = 1; i <= m; i++) {       sort(rec[i].begin(), rec[i].end());       rec[i].push_back(-1);       ord[i] = i;     }     ans = 1ll;     mysort(1, m, 1);     printf( %lld n , ans);     return 0;   }   