Compilare: main.cpp: In function 'int main()': main.cpp:14:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 14 | for(int i = 1; i < s.size(); ++ i) | ~~^~~~~~~~~~ main.cpp:20:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | while(st >= 0 && dr < s.size() && s[st] == s[dr]) | ~~~^~~~~~~~~~ main.cpp:33:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 33 | for(int i = 0; i < s.size(); ++ i) | ~~^~~~~~~~~~