Compilare: main.cpp: In function 'int countvalid()': main.cpp:56:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 56 | for (int i=0; i<s.size(); i++){ | ~^~~~~~~~~ main.cpp:60:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 60 | else if (i==s.size()-1){ | ~^~~~~~~~~~~~ main.cpp:43:9: warning: unused variable 'mult' [-Wunused-variable] 43 | int mult=1, sol=0; | ^~~~