Compilare: main.cpp: In function 'int main()': main.cpp:83:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int it= 0;it!=u->id.size();++it ) ~~^~~~~~~~~~~~~~ main.cpp:25:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ahocorasick.in","r",stdin); ^ main.cpp:26:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ahocorasick.out","w",stdout); ^ main.cpp:27:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s",c); ^ main.cpp:28:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ main.cpp:33:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s",v[i]); ^