Compilare: main.cpp: In function 'int main()': main.cpp:37:19: 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( i = 0; i < s.size(); i++ ) { | ~~^~~~~~~~~~ main.cpp:30:8: warning: variable 'ch' set but not used [-Wunused-but-set-variable] 30 | char ch; | ^~