Compilare: main.cpp: In function 'void dfs(int)': main.cpp:17:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<G[u].size();++i){ ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:26:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.in","r",stdin); ^ main.cpp:27:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.out","w",stdout); ^ main.cpp:31:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ main.cpp:34:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&u,&v); ^