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 VanyaCubes {
public static void main(String[] args) {
   Scanner sc=new Scanner (System.in);
   int n=sc.nextInt();
   int z=0;
   int x=0;
   int a=0;
   for(int i=1;i<=n;i++)
   {
       x=x+i;
       z=z+x;
       if(z<=n)
       {
           ++a;
       }
       else if(z>a)
       {
           break;
       }
   }
    System.out.println(a);
}
    
}
