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 Test1{

    public static void main(String[] args) {
       Scanner user_input = new Scanner(System.in);
       int n = user_input.nextInt();
       int temp = 0; int j = 1;
       while (temp < n){
         int tempu = getFloor(j);
          if(tempu <= n) {   temp = tempu;          }
          else if (tempu > n) {break;}
         j++;   
        }
        System.out.println(j-1);
    }
    public static int getFloor(int n){     
        int sum = 0; 
        for(int j = 1; j <= n; j++){
        for(int i = 1; i <= j; i++){
            sum+=i;
        }
        }
        return sum;
    }
    }
