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>
# n = int(input())
# total = 0
# max = -1
# for i in range(0, n, 1):
#     exit, enter = map(int, input().split())
#     total = total + enter - exit
#     if (total > max):
#         max = total
# print(max)

numberOfCubes = int(input())
sum = 0
cubesOfRow = 0 #so khoi o moi hang
level = 1
while(level < int(numberOfCubes/2) and sum <= numberOfCubes):
    #level khong bao gio vuot qua so khoi chia 2
    cubesOfRow = cubesOfRow+level
    sum = sum + cubesOfRow
    if((sum + cubesOfRow + level + 1) <= numberOfCubes):
        #tong hien tai + (so khoi o dong tiep theo = so khoi hien tai + (level + 1))
        level = level + 1
print(level)


