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 andre {

	public static void main(String args[])
	{
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int count=0;
		int i=1;
		int sum=0;
		while(a>0)
		{	
			sum+=i;
			
			if(a>0 && sum<=a)
			
				{count++;
				
				}
			a = a- (sum);
			i++;
		}
		System.out.println(count);
		
	}
}