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 sol
{
    public static void main(String ar[])
    {
        Scanner scan=new Scanner(System.in);
        int n=scan.nextInt(),s=n;
        int sum=0;
        for(int i=1;i<=n;i++)
        {
            sum+=i;
            s-=sum;
            if(s==0)
            {
                System.out.println(i);
                break;
            }
            else if(s<0)
             {   System.out.println(i-1);break;}
        }
    }
}