Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:31: error: request for member ‘push_back’ in ‘graph.std::vector<_Tp, _Alloc>::operator[] [with _Tp = int, _Alloc = std::allocator<int>](((unsigned int)n1))’, which is of non-class type ‘int’ user.cpp:42: error: request for member ‘size’ in ‘graph.std::vector<_Tp, _Alloc>::operator[] [with _Tp = int, _Alloc = std::allocator<int>](((unsigned int)u))’, which is of non-class type ‘int’ user.cpp:43: error: invalid types ‘int[int]’ for array subscript