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.io.*;
public class Test{
	public static void main(String[] args)throws IOException{
		BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
		int n=Integer.parseInt(br.readLine());
		int l=0;
		int i=1;
		while(n>0){
			int x=i*(i+1)/2;
			i++;
			if(n>=x){
				n-=x;
				l++;
			}else break;
		}
		System.out.println(l);
	}
}
