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.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import javafx.util.Pair;

public class Ahmed {

    public static void main(String[] args) {
            Scanner input=new Scanner (System.in);
            int n=input.nextInt();
            int i=0;
            int c=1;
            int m=0;
            while(i+((c*(c+1))/2)<=n){
                i=i+((c*(c+1))/2);
                c++;
                m++;
            }
            System.out.print(m);
            
    }
    
    
}
    
  