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>

import java.util.Scanner;

public class A {
  public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	long n = sc.nextLong();
	long inc = 1;
	long cnt = 1;
	long cnt1 = 2;
	long res = cnt;
	while(n > res){
	 cnt += cnt1;
	 res = res + cnt;
	 cnt1++;
	 if(n >= res) inc++;
	}
	System.out.println(inc);
}
}
