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>
# def printArr(arr):
# 	for i in range(len(arr)):
# 		print("{}. {}".format(i, arr[i]))
#
#
# import sys
# sys.stdin = open("#input.txt", "r")
n = int(input())

tot = 1
c = 1
i = 1

while True:
	i += 1
	c += i
	tot += c
	if tot > n:
		i -= 1
		break

print(i)