Compilare: user.cpp: In function ‘void trie_insert(std::string)’: user.cpp:41:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sir.size();i++) ^ user.cpp: In function ‘void trie_erase(std::string)’: user.cpp:57:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sir.size();i++) ^ user.cpp: In function ‘int trie_count(std::string)’: user.cpp:73:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sir.size();i++) ^ user.cpp: In function ‘int trie_prefix(std::string)’: user.cpp:82:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sir.size();i++) ^