Compilare: main.cpp: In function 'void ins(std::string)': main.cpp:25:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 25 | for (int i = 0; i < s.size(); i++) | ~~^~~~~~~~~~ main.cpp: In function 'void er(std::string)': main.cpp:39:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 39 | for (int i = 0; i < s.size(); i++) | ~~^~~~~~~~~~ main.cpp: In function 'int ap(std::string)': main.cpp:51:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 51 | for (int i = 0; i < s.size(); i++) | ~~^~~~~~~~~~ main.cpp: In function 'int pref_max(std::string)': main.cpp:61:23: 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.size(); i++) | ~~^~~~~~~~~~