func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     char ch = getchar();     int f = 1, x = 0;     while (ch <  0  || ch >  9 ) {       if (ch ==  - ) f = -1;       ch = getchar();     }     while (ch >=  0  && ch <=  9 ) {       x = (x << 3) + (x << 1) + (ch ^ 48);       ch = getchar();     }     return x * f;   }   bitset<10000> b[60];   int main() {     int m = read(), n = read();     for (int i = 1; i <= m; ++i) {       int k = read();       bool flag = 1;       for (int j = 1; j <= k; ++j) {         int x = read();         b[i][x] = 1;       }       for (int j = 1; j < i; ++j)         if (!(b[i] & b[j]).count()) {           puts( impossible );           return 0;         }     }     puts( possible );     return 0;   }   