Compilare: user.cpp: In function ‘void find_trie(int)’: user.cpp:44:31: warning: unused variable ‘xx’ [-Wunused-variable] int t[30]={0},i=0,value=0,xx=x; trie* a=root; ^ user.cpp: In function ‘int main()’: user.cpp:56:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("xormax.in","r",stdin); ^ user.cpp:57:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("xormax.out","w",stdout); ^ user.cpp:58:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); root=new trie; ^ user.cpp:59:57: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i=1;i<=n;i++) scanf("%d",&t[i]),maxx=max(t[i],maxx); ^