import heapq
 
def getGreatestElements(arr, k):
    heap = []
    ans = []
 
    for i, val in enumerate(arr):
        heapq.heappush(heap, val)
        if len(heap) > k:
            heapq.heappop(heap)
        if i + 1 >= k:
            ans.append(heap[0])
 
    return ans
 
# Example:
# n = 4
# k = 2
# arr = [4, 2, 1, 3]
# n = 5
# k = 4
# arr = [3,2,4,5,1]
n= 5
k=2
arr = [3,1,4,5,2]
print(getGreatestElements(arr, k))  # Output: [2, 2, 3]
 

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