In file included from /usr/include/c++/11/bits/specfun.h:45,
from /usr/include/c++/11/cmath:1935,
from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
from knapsack.cpp:1:
/usr/include/c++/11/bits/stl_algobase.h: In instantiation of 'constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare) [with _Tp = long long int; _Compare = long long int]':
knapsack.cpp:19:35: required from here
/usr/include/c++/11/bits/stl_algobase.h:303:17: error: '__comp' cannot be used as a function
303 | if (__comp(__a, __b))
| ~~~~~~^~~~~~~~~~