Compilare: main.cpp: In function 'int main()': main.cpp:32:12: warning: ignoring return value of 'bool std::stack<_Tp, _Sequence>::empty() const [with _Tp = int; _Sequence = std::deque<int, std::allocator<int> >]', declared with attribute 'nodiscard' [-Wunused-result] 32 | S.empty(); | ~~~~~~~^~ In file included from /usr/include/c++/12.2.1/stack:61, from /usr/include/c++/12.2.1/x86_64-pc-linux-gnu/bits/stdc++.h:89, from main.cpp:1: /usr/include/c++/12.2.1/bits/stl_stack.h:217:7: note: declared here 217 | empty() const | ^~~~~