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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.util.stream.IntStream;

/**
 *
 * @author Prog_Ali
 */
public class codeee {
  

    
    public int sum(ArrayList<Integer> num){
        int sum=0;
        for(int i=0;i<num.size();i++){
         
        sum+=num.get(i);
        }
    return sum;
    
    } 

    /**
     * @param args the command line arguments
     */
   // static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws IOException {
        Scanner input = new Scanner(System.in);
        /*
        int n=input.nextInt();
        int [] arr=new int[n];
         int [] arr2=new int[n];
        for(int i=0;i<n;i++)
        {
        
        arr[i]=input.nextInt();
        arr2[i]=input.nextInt();
        }
        
        int count=0;
        for(int i=0;i<n;i++)
        {
             for(int j=0;j<n;j++)
        {
            if(arr[i]==arr2[j])
            {
            count++;
            }
        }
        }
        
        System.out.println(count);
        }
        
        
        */
ArrayList<Integer> nn=new ArrayList<>();
       int n=input.nextInt();
       nn.add(1);
      
       codeee c=new codeee();
       int level;
       int count=0;
       if(n!=1){
           
       n-=nn.get(0);
       count++;
         for(int i=2;;i++)
         {
             nn.add(i);
           level=c.sum(nn);
               
          n-=level;   
           if(n<0)
          {
          
                   break;   
          }else{
         
       
          
          count++;
        
         
           }
         
         }
         }else{
count=1;
}
       //count=count;
        System.out.println(count);
}
}