Vanya got n cubes. He decided to build a pyramid from them. Vanya wants to build the pyramid as follows: the top level of the pyramid must consist of 1 cube, the second level must consist of 1 + 2 = 3 cubes, the third level must have 1 + 2 + 3 = 6 cubes, and so on. Thus, the i-th level of the pyramid must have 1 + 2 + ... + (i - 1) + i cubes.

Vanya wants to know what is the maximum height of the pyramid that he can make using the given cubes.

Input

The first line contains integer n (1 ≤ n ≤ 104) — the number of cubes given to Vanya.

Output

Print the maximum possible height of the pyramid in the single line.

Examples

Input

1


Output

1


Input

25


Output

4

Note

Illustration to the second sample: 

<image>
num_blocks = int(input())

level = 1
blocks_needed = 1

while blocks_needed <= num_blocks :
    num_blocks -= blocks_needed
    level += 1
    blocks_needed += level

print (level-1)
    
                 
                        
    
            
        

        



            
        
            

        
            



        
        
    
        



            


    
    







    



        
        
        
        


            



        
            

    


    

    



        


        



    
        
        

    







    
    
 

    

        
    
            
    




    


        



    





        
            
        
    
