f k$=($right$$left$+1)$k$=($right$$left$+1)$ is the size of the region to be sorted, then the recursive calls in lines $5$ and $6$ will involve regions of size at most $($k$+1)/2($k$+1)/2.$

If the size of the initial array to be sorted is $256256(2828)$ then the size of the regions to sort recursive calls in lines $5/6$ is $128128.$

if the size of the initial array to be sorted is $1616(2424),$ then during the execution of the algorithm, there will be $44$ calls to mergesort with regions of size $44.$

If the size of the initial array to be sorted is $1616(2424),$ then during the execution of the algorithm, there will be $88$ calls to mergesort with regions of size $11.$