Compilare: user.cpp: In constructor ‘trie::trie(int)’: user.cpp:19:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < tr.size(); i++) ^ user.cpp: In member function ‘void trie::add(std::string)’: user.cpp:27:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) { ^ user.cpp: In member function ‘void trie::rem(std::string)’: user.cpp:40:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) { ^ user.cpp: In member function ‘int trie::ap(std::string)’: user.cpp:51:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) { ^ user.cpp: In member function ‘int trie::ln(std::string)’: user.cpp:63:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) { ^