Short and Easy

Popcount $p(x)$ of a number $x$ is defined as the number of set bits in $x$. For any sequence $ s $ $(s_1,s_2,s_3...s_k) $ of size $k$, let $f(s)$ be defined as the sum of popcount of all its elements. More formally, $f(s) = \sum_{i=1}^{k} p(s_i).$ A positive integer $N$ is given . $N$ can be split into several positive integers that can be represented as sequence $ u$ $(u_1,u_2,u_3..