Compilare: main.cpp: In function 'void add_to_trie(std::string, int, trie*)': main.cpp:17:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | if (index==word.size()) return; | ~~~~~^~~~~~~~~~~~~ main.cpp: In function 'void remove_from_trie(std::string, int, trie*)': main.cpp:30:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | if (index==word.size()-1) return; | ~~~~~^~~~~~~~~~~~~~~ main.cpp: In function 'void longest_prefix(std::string, int&, trie*)': main.cpp:42:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 42 | if (index==word.size()) return; | ~~~~~^~~~~~~~~~~~~