Compilare: main.cpp: In constructor 'BigNumber::BigNumber(std::string)': main.cpp:71:30: 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] 71 | for(ll i = 0 ; i < number.size() ; i++) | ~~^~~~~~~~~~~~~~~