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>
# URL: http://codeforces.com/problemset/problem/492/A
# ~ Basic Implementation Problem

def parse_input() -> int:
    return int(input())


def _solve(n: int, h: int) -> int:
    w = int(h*(h+1)/2)
    if n < w:
        return h - 1
    return _solve(n - w, h + 1)


def solve(n: int) -> int:
    return _solve(n, 1)


if __name__ == '__main__':
    print(solve(parse_input()))
