Compilare: main.cpp: In function 'int main()': main.cpp:62:18: warning: ignoring return value of 'constexpr std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; reference = std::pair<int, int>&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result] 62 | rez[k]; | ^ In file included from /usr/include/c++/12.2.1/vector:64, from /usr/include/c++/12.2.1/functional:62, from /usr/include/c++/12.2.1/x86_64-pc-linux-gnu/bits/stdc++.h:71, from main.cpp:1: /usr/include/c++/12.2.1/bits/stl_vector.h:1121:7: note: declared here 1121 | operator[](size_type __n) _GLIBCXX_NOEXCEPT | ^~~~~~~~