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.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
public final class Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner reader=new Scanner(System.in);
		int f=reader.nextInt();
		int levsum=0;
		int nocubes=f;
		int sumofcubes=1;
		if (f==0)
		System.out.println(0);
	  int	i=1;
		while(nocubes>=sumofcubes){
		    i++;
		    
		    levsum=levelsum(i);
		 //   System.out.println((levsum));
		    sumofcubes=levsum+sumofcubes;
		    
		    
		}
		
		
		
		System.out.println((i-1));
	}
	
	public static int levelsum(int level)
	{   int i=0;
	    int sum=0;
	        for(i=1;i<=level;i++)
	        {
	        sum=i+sum;
	        }
	
	     return sum;
	}
}
