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.util.*;
import java.math.BigInteger;

public class Test{
	public static void main(String []args){
		Scanner cin=new Scanner(System.in);
		int n=cin.nextInt();
		int res=0, total=0, realTotal=0;
		boolean go=true;
		while(go){
	        for(int i=1;i<Integer.MAX_VALUE;i++){
	        	total+=i;
	        	realTotal+=total;
	        	res++;
	        	if(realTotal==n){
	        		go=false;
	        		break;
	        	}
	        	if(realTotal>n){
	        		res--;
	        		go=false;
	        		break;
	        	}
	        }
		}
		System.out.println(res);
	}
}