Compilare: user.cpp: In function ‘int query(int, int)’: user.cpp:75:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] node = alf[node][ch]; ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:12:43: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, SIZE, 1, input_file); ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:34:47: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, SIZE, 1, input_file); ^