Your task is to construct a building which will be a pile of n cubes.
The cube at the bottom will have a volume of n^3, the cube above 
will have  volume of (n-1)^3 and so on until the top which will have a volume of 1^3.

You are given the total volume m of the building.
Being given m can you find the number n of cubes you will have to build?

The parameter of the function findNb `(find_nb, find-nb, findNb)` will be an integer m
and you have to return the integer n such as
n^3 + (n-1)^3 + ... + 1^3 = m
if such a n exists or -1 if there is no such n.

## Examples:
```
findNb(1071225) --> 45
findNb(91716553919377) --> -1
```

Difficulty: EASY
Starter code: def find_nb(m):
	

Solutions:
def find_nb(m):
	n = 1
	volume = 0
	while volume < m:
		volume += n ** 3
		if volume == m:
			return n
		n += 1
	return -1


def find_nb(m):
	n = s = 0
	while True:
		n += 1
		s += n
		k = s * s
		if k == m:
			return n
		elif k > m:
			return -1


def find_nb(m):
	(i, sum) = (1, 1)
	while sum < m:
		i += 1
		sum += i ** 3
	return i if m == sum else -1


def find_nb(m):
	n = int((2 * m ** 0.5) ** 0.5)
	if (n * (n + 1) // 2) ** 2 != m:
		return -1
	return n


def find_nb(m):
	(total, i) = (1, 2)
	while total < m:
		total += i * i * i
		i += 1
	return i - 1 if total == m else -1


def find_nb(m):
	n = 0
	while m > 0:
		n += 1
		m -= n ** 3
	return n if m == 0 else -1


def find_nb(m):
	l = 1
	while m > 0:
		m -= l ** 3
		l += 1
	return l - 1 if m == 0 else -1


def find_nb(m):
	try:
		vol = int(m)
	except TypeError:
		return -1
	partial_sum = 0
	i = 0
	while partial_sum < vol:
		i += 1
		partial_sum += i ** 3
	if vol == partial_sum:
		return i
	else:
		return -1


from decimal import *

def find_nb(m):
	getcontext().prec = 24
	squareRootM = Decimal(m).sqrt()
	squareRootDelta = Decimal(1 + 8 * squareRootM).sqrt()
	num = (squareRootDelta - 1) / 2
	return num if num % 1 == 0 else -1