Compilare: user.cpp: In function ‘int main()’: user.cpp:78:44: warning: operation on ‘K’ may be undefined [-Wsequence-point] S[Q[K].z] = D1[i & 1][Q[K++].y]; ^ user.cpp:51:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "inversari.out", "w", stdout ); ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:17:47: 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); ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:39:51: 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); ^