Compilare: main.cpp: In function 'void insert(TrieNode*, std::__cxx11::string)': main.cpp:29:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<key.length();i++) ~^~~~~~~~~~~~~ main.cpp: In function 'bool erase(TrieNode*, std::__cxx11::string, int)': main.cpp:52:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(level==key.size()) ~~~~~^~~~~~~~~~~~ main.cpp: In function 'int search(TrieNode*, std::__cxx11::string)': main.cpp:76:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<key.length();i++) ~^~~~~~~~~~~~~ main.cpp: In function 'int count(TrieNode*, std::__cxx11::string)': main.cpp:89:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<key.length();i++) ~^~~~~~~~~~~~~