CF873D Merge Sort

Merge sort is a well-known sorting algorithm. The main function that sorts the elements of array $ a $ with indices from $ [l,r) $ can be implemented as follows: 1. If the segment $ [l,r) $ is already sorted in non-descending order (that is, for any $ i $ such that $ l

The first line contains two numbers $ n $ and $ k $ ( $ 1

If a permutation of size $ n $ such that there will be exactly $ k $ calls of $ mergesort $ while sorting it doesn't exist, output $ -1 $ . Otherwise output $ n $ integer numbers $ a[0],a[1],...,a[n-1] $ — the elements of a permutation that would meet the required conditions. If there are multiple answers, print any of them.