Compilare: user.cpp: In function ‘void dfs_pls(int)’: user.cpp:12:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<vecin[k].size();i++) ^ user.cpp: In function ‘void dfs_mns(int)’: user.cpp:20:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<wecin[k].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:33:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in","r",stdin); ^ user.cpp:34:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out","w",stdout); ^ user.cpp:35:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&n,&m); ^ user.cpp:38:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&i,&j); ^