Compilare: main.cpp: In function 'void ins(std::string)': main.cpp:19:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 19 | for (int i=0;i<s.size();i++){ | ~^~~~~~~~~ main.cpp: In function 'void del(std::string)': main.cpp:31:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 31 | for (int i=0;i<s.size();i++){ | ~^~~~~~~~~ main.cpp: In function 'int appear(std::string)': main.cpp:41:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 41 | for (int i=0;i<s.size();i++){ | ~^~~~~~~~~ main.cpp: In function 'int pref(std::string)': main.cpp:54:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 54 | for (int i=0;i<s.size();i++){ | ~^~~~~~~~~