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.io.*;
import java.util.*;

public class ok
{

	public static  void main(String agrs[])
	{




		int n;
		Scanner s=new Scanner(System.in);
n=s.nextInt();

int count=0;

		int sum=0;
		int sum2=0;

int i=1;
	while(sum2<=n)
{
sum=sum+i;

sum2=sum2+sum;



count++;

i=i+1;




		}

		System.out.println(count-1);
	}
}