Compilare: main.cpp: In function 'void dfs(int)': main.cpp:9:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<l[x].size();i++) ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:25:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<c.size();++i) ~^~~~~~~~~ main.cpp:16:37: 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:17:39: 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:18:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ main.cpp:20:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^