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.*;

import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
	    int n = sc.nextInt();
	    int num = 0;
	    int count =0;
	    int i = 1;
	    while(n >= (num+i)) {
	    	count++;
	    	num+=i;
	    	n-=num;
	    	i++;
	    }
	    System.out.println(count);
	   
	    
	    
		

	}
	public static String reverse(String a) {
		char[] b = a.toCharArray();
		String c = "";
		for(int i = b.length-1; i >= 0 ;i--) {
			c+=b[i];
		}
		return c;
	}
	public static int min(int a, int b,int c) {
		if(a <b && a <c) {
			return a;
		}
		if(b <a && b <c) {
			return b;
		}
		return c;
	}
}
