Compilare: main.cpp: In function 'int main()': main.cpp:57:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 57 | for (int i = 0; i < s.size(); ++i) { | ~~^~~~~~~~~~ main.cpp: In function 'bool FACT()': main.cpp:52:16: warning: 'res' may be used uninitialized [-Wmaybe-uninitialized] 52 | return res; | ^~~ main.cpp:37:14: note: 'res' was declared here 37 | bool res; | ^~~