Compilare: main.cpp: In function 'void add_string_to_trie(std::__cxx11::string&)': main.cpp:49:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<to_add.length(); i++) ~^~~~~~~~~~~~~~~~ main.cpp: In function 'std::__cxx11::string search_prefix(std::__cxx11::string)': main.cpp:103:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<prefix.length(); i++) ~^~~~~~~~~~~~~~~~ main.cpp: In function 'void add_relevancy(std::__cxx11::string, int)': main.cpp:125:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<user.length(); i++) ~^~~~~~~~~~~~~~ main.cpp: In function 'void read()': main.cpp:149:13: warning: unused variable 'price' [-Wunused-variable] int price; ^~~~~