Compilare: user.cpp: In function ‘void dfsgraph(int)’: user.cpp:18:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<gr[node].size();i++) ^ user.cpp: In function ‘void dfstrans(int)’: user.cpp:29:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<tr[node].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:64:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<ctc[i].size();j++) ^ user.cpp:37:32: 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:38:34: 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:39:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:42:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^