In file included from /nix/gcc-13.3.0/include/c++/13.3.0/algorithm:60,
                 from stdc++.h:51:
In function ‘const _Tp& std::max(const _Tp&, const _Tp&) [with _Tp = long long int]’,
    inlined from ‘int main()’ at foo.cc:28:18:
/nix/gcc-13.3.0/include/c++/13.3.0/bits/stl_algobase.h:262:7: warning: ‘res’ may be used uninitialized [-Wmaybe-uninitialized]
  262 |       if (__a < __b)
      |       ^~
foo.cc: In function ‘int main()’:
foo.cc:25:8: note: ‘res’ was declared here
   25 |     ll res, prod = items[0].a;
      |        ^~~