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.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeSet;
import java.util.Vector;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Hasan0504 {

    // public static Scanner input = new Scanner(System.in);
    public static void main(String[] args)
            throws IOException {

        Scanner input = new Scanner(System.in);
    // BufferedReader buffer=new BufferedReader(new InputStreamReader(System.in));
    int n=input.nextInt();
    int h=0;
    if(n==1){
        System.out.println("1");
        return;
    }
    int c=0;
    int x=0;
 
    for(int i=1;i<=n;i++){
        for(int ii=1;ii<=i;ii++){
            c+=ii;
        }
      h+=c;
      if(h<=n)
          x++;
      else
          break;
        c=0;
    }
        System.out.println(x); 
    }
 
}