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 func(n):
	x = n*(n+1)
	x = x//2
	return x

arr = [1]
cnt = 2
while True:
	x = func(cnt)
	x+=arr[-1]
	if x>10**4:
		break
	else:
		arr.append(x)
	cnt+=1
		
n = int(input())
cnt = 1
for i in arr:
	if i<=n:
		ans = cnt
	else:
		break
	cnt+=1
print(ans)