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#61 Build a pile of Cubes 

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

public class ASum {
	
	public static long findNb(long m) {
		// your code
		long sum = 0;
		int n = 0;
		while (sum < m) 
			sum += (long) Math.pow(++n, 3);
		return sum == m ? n : -1;
	}
}