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 Main{
	static Scanner scan = new Scanner(System.in);
	public static void solve()
	{
		int n = scan.nextInt();
		int c=0;
		if(n==0)
		{
			System.out.println(0);
			return;
		}
		int a=0;
		while(true)
		{
			int x = c*(c+1)/2;
			if(a+x>n)
			{
				System.out.println(c-1);
				return;
			}
			a=a+x;
			c++;
		}
	}
	public static void main(String[] args)
	{
		
		//int t = scan.nextInt();
		int t = 1;
		while(t-->0)
		{
			solve();
		}
	}
}