Compilare: main.cpp: In function 'void insert_word(std::__cxx11::string)': main.cpp:14:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < word.size();i ++) ~~^~~~~~~~~~~~~ main.cpp: In function 'void delete_word(std::__cxx11::string)': main.cpp:26:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); i ++) ~~^~~~~~~~~~~~~ main.cpp: In function 'int word_query(std::__cxx11::string)': main.cpp:37:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size(); i ++) ~~^~~~~~~~~~~~~ main.cpp: In function 'int prefix_query(std::__cxx11::string)': main.cpp:48:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < word.size();i ++) ~~^~~~~~~~~~~~~