Codeforces Round #280 (Div. 2) A_html/css_WEB-ITnose

题目：

A. Vanya and Cubes

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

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.

Sample test(s)

input

output

input

25

output

Note

Illustration to the second sample:

没啥好说的。模拟一下就可以了，还wa一发不应该..

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