Compilare: user.cpp: In function ‘int main()’: user.cpp:64:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<ans.size();i++) ^ user.cpp:12:35: 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:13:37: 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:16:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:19:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&u,&w); ^