Compilare: main.cpp: In function 'void add(int, std::string&, trie*)': main.cpp:17:11: 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 (i == s.size()) { | ~~^~~~~~~~~~~ main.cpp: In function 'bool del(int, std::string&, trie*)': main.cpp:32:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 32 | if (i == s.size()) { | ~~^~~~~~~~~~~ main.cpp: In function 'int cnt(int, std::string&, trie*)': main.cpp:53:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 53 | if (i == s.size()) | ~~^~~~~~~~~~~ main.cpp: In function 'int pref(int, std::string&, trie*)': main.cpp:61:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 61 | if (i == s.size()) | ~~^~~~~~~~~~~