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.Scanner;

public class CodeForces {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int cubes = 0;
        int counter = 1;
        int total = 0;

        while (total <= n){
            cubes += counter;
            if((total + cubes) > n){
                break;
            }
            total += cubes;
            ++counter;
        }

        System.out.println(counter-1);


    }

    public static boolean inArray(int element, int[] array){
        for (int i : array) {
            if(i == element){
                return true;
            }
        }
        return false;
    }

    public static boolean isPrime(int number){
        if(number == 2 || number == 3){
            return true;
        }

        if(number % 2 == 0){
            return false;
        }

        int sqrt = (int) Math.sqrt(number) + 1;
        for (int i = 3; i < sqrt; i += 2) {
            if(number % i == 0){
                return false;
            }
        }

        return true;
    }


}
