Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:43:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<V[nod].size();++i) ^ user.cpp: In function ‘void sort_top(int)’: user.cpp:53:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < G[x].size();++i) ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:32:51: 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); ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:10:47: 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); ^