prison.cpp: In function 'std::vector<std::vector<int> > devise_strategy(int)':
prison.cpp:6:16: error: 'vector' was not declared in this scope
    6 |         vector<vector<int>> a(N + 1, vector<int>(N + 1, 0));
      |                ^~~~~~
prison.cpp:6:16: note: suggested alternatives:
In file included from /usr/include/c++/13/vector:66,
                 from prison.h:1,
                 from prison.cpp:1:
/usr/include/c++/13/bits/stl_vector.h:428:11: note:   'std::vector'
  428 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
/usr/include/c++/13/vector:86:13: note:   'std::pmr::vector'
   86 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
prison.cpp:6:23: error: expected primary-expression before 'int'
    6 |         vector<vector<int>> a(N + 1, vector<int>(N + 1, 0));
      |                       ^~~
prison.cpp:7:37: error: 'a' was not declared in this scope
    7 |         for(int i = 0; i <= N; i++) a[0][i] = i;
      |                                     ^
prison.cpp:8:37: error: 'a' was not declared in this scope
    8 |         for(int i = 1; i <= N; i++) a[i][0] = 1;
      |                                     ^
prison.cpp:12:38: error: 'a' was not declared in this scope
   12 |                         if(j <= cnt) a[i][j] == -2;
      |                                      ^
prison.cpp:13:30: error: 'a' was not declared in this scope
   13 |                         else a[i][j] = -1;
      |                              ^
prison.cpp:16:16: error: 'a' was not declared in this scope
   16 |         return a;
      |                ^