Compilare: main.cpp: In instantiation of 'T& Vector<T>::operator[](int) [with T = long long int]': main.cpp:55:33: required from here main.cpp:20:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int, std::allocator<long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | if (index > this->size()-1) { | ~~~~~~^~~~~~~~~~~~~~~~