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.Scanner;

public class Cubves {
	public static void main(String[] args) {

		Scanner s = new Scanner(System.in);

		int n = s.nextInt();
		int c = 0;
		int l=0;
		
		int i=0;
		
		while(n>0)
		{
			i++;
			c=l+i;
			l=c;
			n-=c;
			
			if(n<0)
			{
				i--;
			}
			
		}
		System.out.println(i);
		
	}

}
