Compilare: user.cpp: In function ‘int main()’: user.cpp:60:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(index[B[i]]<pos[B[i]].size()&&pos[B[i]][index[B[i]]]<pos[B[i-1]][index[B[i-1]]]) ^ user.cpp:62:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(index[B[i]]==pos[B[i]].size()){ ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:12:47: 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:34:51: 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); ^