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 Cubes {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        String s = input.next();
        int Cubes = Integer.parseInt(s);
        int Count = 0;
        if (Cubes == 1) {

            Count++;

        }

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

            int level = i * (i + 1) / 2;
            
            if (Cubes>= level){
            Cubes -= level;
            Count++;
            }
        }

        System.out.println(Count);
    }

}