Compilare: main.cpp: In function 'bool vef(long long int, std::string)': main.cpp:18:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 18 | for(int x = 0;x<a.size();++x) | ~^~~~~~~~~ main.cpp:17:9: warning: unused variable 'cnt' [-Wunused-variable] 17 | int cnt = 0; | ^~~ main.cpp: At global scope: main.cpp:57:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] 57 | main() | ^~~~