Compilare: main.cpp: In member function 'void trie::insert(std::string)': main.cpp:42:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 42 | for (int i=0; i<s.size(); ++i) { | ~^~~~~~~~~ main.cpp: In member function 'void trie::erase(std::string)': main.cpp:53:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 53 | for (int i=0; i<s.size(); ++i) { | ~^~~~~~~~~ main.cpp: In member function 'int trie::search(std::string)': main.cpp:62:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 62 | for (int i=0; i<s.size(); ++i) { | ~^~~~~~~~~ main.cpp: In member function 'int trie::prefix(std::string)': main.cpp:71:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 71 | for (int i=0; i<s.size(); ++i) { | ~^~~~~~~~~