Compilare: user.cpp: In function ‘int DFS(int)’: user.cpp:53:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < G[x].size(); ++ i) ^ user.cpp: In function ‘int main()’: user.cpp:75:12: warning: suggest parentheses around assignment used as truth value [-Wparentheses] ok = k = 0; ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:19:43: 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:46:47: 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); ^