Compilare: user.cpp: In function ‘int df(int)’: user.cpp:16:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[x].size() ; ++i) ^ user.cpp: In function ‘int main()’: user.cpp:80:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino2.in" , "r" , stdin); ^ user.cpp:81:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino2.out" , "w" , stdout); ^ user.cpp:83:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n); ^