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.*;

public class VanyaAndCubes {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int cubes = sc.nextInt();
		sc.close();
		int sum = 0;
		int total = 0;
		int count = 0;
		for(int i=1; i<=10000; i++) {
			sum = sum + i;
			total = total + sum;
			if(total <= cubes) count++;
			else break;
		}
		
		System.out.println(count);
	}
}
