Compilare: main.cpp: In instantiation of 'Range_minimum_query<T>::Range_minimum_query(std::vector<T>&) [with T = int]': main.cpp:46:35: required from here main.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < arr.size(); i++) { main.cpp:23:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 1; j < lookup[0].size(); j++) { main.cpp:24:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i <= lookup.size() - (1 << j); i++) { ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~