jetpack.cpp: In function 'int main()':
jetpack.cpp:23:10: error: invalid use of non-static member function 'std::vector<_Tp, _Alloc>::size_type std::vector<_Tp, _Alloc>::size() const [with _Tp = int; _Alloc = std::allocator<int>; std::vector<_Tp, _Alloc>::size_type = long unsigned int]'
23 | cout << res.size << '\n';
| ~~~~~^~~~~~~~~~~
In file included from /usr/include/c++/10/vector:67,
from /usr/include/c++/10/functional:62,
from /usr/include/c++/10/pstl/glue_algorithm_defs.h:13,
from /usr/include/c++/10/algorithm:74,
from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:65,
from jetpack.cpp:1:
/usr/include/c++/10/bits/stl_vector.h:918:7: note: declared here
918 | size() const _GLIBCXX_NOEXCEPT
| ^~~~
jetpack.cpp:24:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
24 | for(int i = 0;i < res.size(); i++) cout << res[i] << ' ' << 1 << '\n';;
| ~~^~~~~~~~~~~~