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.Scanner;

public class Main {//CF280A
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		
		int n = in.nextInt();
		int min = 1;
		int height = 1;
		ArrayList<Integer> list = new ArrayList<>();
		list.add(min);
		for(int i =2;;i++){
			min = min+i;
			if(min<=n){
				list.add(min);
				//height++;
			}else{
				break;
				}
		}//1,3,6,10,15,21,28,36
		
		int sum=1;
		for(int i =1;i<list.size();i++){
			sum =sum+ list.get(i);
			//System.out.print(sum+" ");
			if(sum >n){
				break;
			}
			height++;
		}
		System.out.println(height);
		
	}
}
