Compilare: main.cpp: In instantiation of 'void FenwickTree<T, neutral_val, BinaryOperation>::update(int, T) [with T = long long int; T neutral_val = 0; BinaryOperation = main()::<lambda(int, int)>]': main.cpp:53:26: required from here main.cpp:20:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | for (int i = index + 1; i < tree.size(); i += i & -i) { | ~~^~~~~~~~~~~~~