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>

//package codeforces;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;

public class Flo {

    public int GCD(int a, int b) {
        if (b == 0) {
            return a;
        }
        return GCD(b, a % b);
    }
// int[] printDivisors(int n) 
//{ 
//   ArrayList<Integer> list=new ArrayList<Integer>();
//    int t=0;
//    for (int i=1;i<=n;i++) 
//        if (n%i==0) 
//        {
//          list.add(i);
//        }
//   ;
//} 

    public static void main(String[] args) throws IOException {
        Flo obj = new Flo();
        Scanner in = new Scanner(System.in);
       
        int t = in.nextInt();
       int total=0,i=1;
       while(true)
       {
           total=total+(i*(i+1))/2;
           if(total==t)
           {
               break;
           }
           else if(total>t)
           {
               i--;
               break;
             
           }
           else
           {
               i++;
           }
       }
        System.out.println(""+i); 
    }
}
