Compilare: main.cpp: In function 'int main()': main.cpp:15:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 15 | for (int i=0; i<s.size(); i++) | ~^~~~~~~~~ main.cpp:17:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | for (int i=0; i<s.size(); i++) | ~^~~~~~~~~ main.cpp:22:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 22 | while (st>=0 && dr<s.size() && s[st]==s[dr]) | ~~^~~~~~~~~ main.cpp:30:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | while (st>=0 && dr<s.size() && s[st]==s[dr]) | ~~^~~~~~~~~