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.*;
public class A_492 
{
	public static void main(String [] args)
	{
		Scanner in = new Scanner (System.in);

		int n = in.nextInt();

		int sum = 0;
		int temp = 1;
		int temp1 = 0;
		int temp2 = 0;

		while(sum<=n)
		{

			if(temp1<=n)
			{
				sum = sum + temp;
				temp++;
				temp1 = temp1 + sum;
				temp2++;
			}
			else
			{
				break;
			}

		}
		System.out.println(temp2-1);

	}
}
