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 math
import sys
from sys import *
from bisect import insort
import heapq
import collections
from collections import deque, defaultdict, Counter
from itertools import permutations, combinations, combinations_with_replacement
import random
import os

mod = 10**9+7 #1000000007
MAX = sys.maxsize #maximum size
MIN = -sys.maxsize-1 #minimum size

#----------Check Prime numbers----------------
def isPrime(n):
    if n>1:
        for i in range(2,n):
            if (n%i) == 0:
                return False
        else:
            return True
    else:
        return False
#----------Check Panagram-----------------------
def isPanagram(s):
    alphabet = 'abcdefghijklmnopqrstuvwxyz'
    for char in alphabet:
        if char not in s.lower():
            return False
    return True

#----------List with same elements--------------
def isEqual(list1):
    if len(list1)<0:
        res = True
    res = all(ele == list1[0] for ele in list1)
    if(res):
        return True
    else:
        return False

#-----Removing duplicate elements from a list---
def remove_duplicate(list1):
    final_list = []
    for i in list1:
        if i not in final_list:
            final_list.append(i)
    return final_list%mod

#-----------------Solve it----------------------
def solve():
    n = int(input())
    i, current, last = 0, 0, 0
    while(n>0):
        i+=1
        current = last + i
        last = current
        n -=current
        if n<0:
            i -=1
    return i
#------------------Main-------------------------
if __name__ == '__main__':
    #t = int(stdin.readline())
    #for i in range (t):
        result = solve()
        stdout.write(str(result)+'\n')
