PROBLEM STATEMENT
You are given a vector <int> divisors containing K elements. Find a positive integer n such that 
exactly K-1 elements of divisors are exact divisors of n. If there are several such numbers n, 
return the smallest possible one. If no such number n exists, return -1 instead.

DEFINITION
Class:AllButOneDivisor
Method:getMinimum
Parameters:vector <int>
Returns:int
Method signature:int getMinimum(vector <int> divisors)


NOTES
-A number x is an exact divisor of y if y divided by x yields an integer result.
-If x is an exact divisor of y then we call y a multiple of x.


CONSTRAINTS
-divisors will contain between 2 and 6 elements, inclusive.
-Each element of divisors will be distinct.
-Each element of divisors will be between 1 and 15, inclusive.


EXAMPLES

0)
{2,3,5}

Returns: 6

There are many possible values for n in this case. For example: 6, 15, 75 and 12. 6 is the 
smallest of them.


1)
{2,4,3,9}

Returns: 12



2)
{3,2,6}

Returns: -1

Every multiple of 3 and 2 is also a multiple of 6.
Every multiple of 6 is also a multiple of 2 and 3.

Therefore, a number that is a multiple of exactly 2 out of the three elements in this array cannot 
exist.

3)
{6,7,8,9,10}

Returns: 360



4)
{10,6,15}

Returns: -1



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