Compilare: main.cpp: In function 'void dfs(int, int)': main.cpp:42:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sons[node].size();i++) ~^~~~~~~~~~~~~~~~~~ main.cpp: In constructor 'InputReader::InputReader(const char*)': main.cpp:13:47: 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); ^ main.cpp: In member function 'void InputReader::advance()': main.cpp:35:51: 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); ^