Compilare: main.cpp: In function 'int main()': main.cpp:26:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 26 | for(int i=0; i<s.size(); i++) | ~^~~~~~~~~ main.cpp:37:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | for(int i=2*l-1; i<s.size(); i++) | ~^~~~~~~~~