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 CodeForces
{
	public static void main(String args[])
	{
		Scanner input = new Scanner(System.in);
		int n = input.nextInt();
		ArrayList<Integer> list = new ArrayList<>();
		for (int i = 1; i < 100; i++)
		{
			list.add(i * (i + 1) * (i + 2) / 6);
		}
		for (int i = 0; i < list.size() - 1; i++)
		{
			if (list.get(i) <= n && n < list.get(i + 1))
			{
				System.out.println(i + 1);
				break;
			}
		}
	}
}