def exchange_elements(lst):
    from itertools import zip_longest, chain, tee
    
    lst1, lst2 = tee(iter(lst), 2)
    return list(chain.from_iterable(zip_longest(lst[1::2], lst[::2])))
def heap_queue_largest(nums,n):
  import heapq as hq
  
  largest_nums = hq.nlargest(n, nums)
  return largest_nums