Compilare: user.cpp: In function ‘trie* Insert(trie*, char*)’: user.cpp:25:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) ^ user.cpp: In function ‘int main()’: user.cpp:51:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("virus.in","r",stdin); ^ user.cpp:52:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("virus.out","w",stdout); ^ user.cpp:53:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&l,&n); ^ user.cpp:54:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",s); ^ user.cpp:57:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^ user.cpp:58:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",str); ^