Compilare: main.cpp: In function 'void insert_word(std::__cxx11::string)': main.cpp:34:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<s.size();i++) ~^~~~~~~~~ main.cpp: In function 'void delete_word(std::__cxx11::string)': main.cpp:52:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<s.size();i++) ~^~~~~~~~~ main.cpp:61:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i==s.size()) ~^~~~~~~~~~ main.cpp:65:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i++;i<=s.size();i++) ~^~~~~~~~~~ main.cpp:67:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i==s.size()) ~^~~~~~~~~~ main.cpp: In function 'int find_word(std::__cxx11::string)': main.cpp:85:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<s.size();i++) ~^~~~~~~~~ main.cpp: In function 'int longest_prefix(std::__cxx11::string)': main.cpp:102:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<s.size();i++) ~^~~~~~~~~