Compilare: user.cpp: In function ‘void DFS(long int)’: user.cpp:25:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(long i=0;i<list[nod].size();i++){ ^ user.cpp: In function ‘int main()’: user.cpp:82:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ans.size() != n+1){ ^ user.cpp:46:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino.in","r",stdin); ^ user.cpp:47:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino.out","w",stdout); ^ user.cpp:49:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld",&n); ^ user.cpp:51:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld",&x,&y); ^