In file included from /usr/include/c++/12/vector:64,
                 from /usr/include/c++/12/queue:61,
                 from /usr/include/x86_64-linux-gnu/c++/12/bits/stdc++.h:86,
                 from /in/foo.cc:1:
In member function 'void std::vector<_Tp, _Alloc>::clear() [with _Tp = int; _Alloc = std::allocator<int>]',
    inlined from 'int main()' at /in/foo.cc:38:23:
/usr/include/c++/12/bits/stl_vector.h:1601:24: warning: iteration 1004 invokes undefined behavior [-Waggressive-loop-optimizations]
 1601 |       { _M_erase_at_end(this->_M_impl._M_start); }
      |         ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:2:33: note: within this loop
    2 | #define rep(i,a,b) for(int i=a;i<=b;i++)
      |                                 ^
/in/foo.cc:37:9: note: in expansion of macro 'rep'
   37 |         rep(i,1,maxn)
      |         ^~~