Compilare: main.cpp: In function 'int main()': main.cpp:29:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 29 | for ( int i = 0 ; i < a.size() ; i ++) | ~~^~~~~~~~~~