func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class t>   t mag(t a) {     return a > 0 ? a : -a;   }   template <class T, class U>   T cdiv(T num, U den) {     return (num / den) + ((num % den) > 0);   }   std::ifstream term( /dev/tty );   std::string tempstring;   using ll = int_fast64_t;   using ii = pair<int, int>;   using vi = vector<int>;   using vl = vector<ll>;   using vii = vector<ii>;   const int sij = 60;   const ll mod = 1000000007ll;   vi took[sij];   int m, n;   int esc(int tcase) {     cin >> m >> n;     for (auto i = 0; i != m; i++) {       int tp;       cin >> tp;       for (auto j = 0; j != tp; j++) {         int k;         cin >> k;         took[i].push_back(k);       }       sort(took[i].begin(), took[i].end());     }     for (auto i = 0; i != m - 1; i++) {       set<int> vv;       ;       for (auto &e : took[i]) {         for (auto j = i + 1; j != m; j++) {           ;           ;           if (binary_search(took[j].begin(), took[j].end(), e)) {             vv.insert(j);           }         }       };       if (vv.size() + i + 1 != m) {         cout <<  impossible n ;         exit(0);       }     }     cout <<  possible n ;     return 0;   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int tc = 1;     for (int i = 1; i <= tc; i++) esc(i);   }   