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>
import sys
import os


def changeStdioToFile():
    path = os.path.dirname(os.path.abspath(__file__))
    sys.stdin = open(f'{path}/input.txt', 'r')
    sys.stdout = open(f'{path}/output.txt', 'w')


# changeStdioToFile()
t = 1
# t = int(input())
for _ in range(t):
	n = int(input())
	i = 1
	res = 0
	base = i
	while n - base >= 0:
		n -= base
		i += 1
		res+=1
		base += i
	print(res)
		
