# find k greatest number from a list
# i/p : arr = [7,10,4,3,20,15], k = 3
# o/p : [20,15,10]

import heapq
k=3
a = [7,10,4,3,20,15]
r =[]


for i,v in enumerate(a):
  heapq.heappush(r,v)
  if  k<(i+1):
    heapq.heappop(r)
     
arr=[heapq.heappop(r) for i in range(k)]  
 
print(arr)




    
