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 static java.lang.Integer.min;

import static java.lang.Math.abs;

import java.util.Scanner;



public class Main {



    public static void main(String[] args) {

        Scanner in=new Scanner(System.in);

        int n,m;

        int NN=11111;

        n=in.nextInt();

        int sum=0;

        int ans = 0;

        for(int i=1;i<=NN;i++) {

            sum+=i*(i+1)/2;

            if(sum<=n) ans=i;

            else break;

        }

        System.out.println(ans);

        

    }

}
   