Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:13:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<a[x].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:30:10: warning: unused variable ‘ok’ [-Wunused-variable] bool ok=false; ^ user.cpp:27:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("asmax.in","r",stdin); ^ user.cpp:28:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("asmax.out","w",stdout); ^