Compilare: main.cpp: In function 'void add(std::string)': main.cpp:29:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 29 | for(int i=0; i<s.length(); i++){ | ~^~~~~~~~~~~ main.cpp: In function 'void del(std::string)': main.cpp:48:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 48 | for(int i=0; i<s.length(); i++){ | ~^~~~~~~~~~~ main.cpp: In function 'int app(std::string)': main.cpp:61:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 61 | for(int i=0; i<s.length(); i++){ | ~^~~~~~~~~~~ main.cpp: In function 'int pref(std::string)': main.cpp:86:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 86 | for(int i=0; i<s.length(); i++){ | ~^~~~~~~~~~~