Compilare: user.cpp: In function ‘void I(Trie*, char*)’: user.cpp:28:9: warning: variable ‘a’ set but not used [-Wunused-but-set-variable] int a=0; ^ user.cpp: In function ‘int main()’: user.cpp:55:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.in", "r", stdin); ^ user.cpp:56:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.out", "w", stdout); ^ user.cpp:57:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^ user.cpp:62:18: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); ^ /tmp/cc3bDzf6.o: In function `main': user.cpp:(.text.startup+0xa0): warning: the `gets' function is dangerous and should not be used.