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>

//package codeforcess.comp_1dec;

import java.util.Scanner;

public class ankit {

    public static void main(String[] args) {
        // TODO code application logic here
        Scanner s= new Scanner(System.in);
        int no=s.nextInt();
        int sum=0;
        int n=0;
        int val=0;
        while(sum<=no)
        {++n;
        sum=sum+(n*((2)+(n-1)))/2;
            val++;
        }
        System.out.println(--val);
    }
    
}
