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>
# -*- coding: utf-8 -*-
"""
Created on Sat Aug  1 12:33:14 2020

@author: alber
"""


def sumaaritmetica(n):
       return (n)*(n+1)/2
   
def sumadesumas(n):
    
    if n == 1:
        return 1 
    
    
    return sumaaritmetica(n) + sumadesumas(n-1)


cubos = int(input())
i = 1
while cubos - sumadesumas(i) >= 0:
    i+=1
    
print(i-1)
    
    
    
    

   
    
    
    
















    