write a go solution for Description:
To defeat Lord Voldemort, Harry needs to destroy all horcruxes first. The last horcrux is an array a of n integers, which also needs to be destroyed. The array is considered destroyed if all its elements are zeroes. To destroy the array, Harry can perform two types of operations:

1. choose an index i (1<=i<=n), an integer x, and subtract x from a_i.
2. choose two indices i and j (1<=i,j<=n;inej), an integer x, and subtract x from a_i and x+1 from a_j.

Note that x does not have to be positive.

Harry is in a hurry, please help him to find the minimum number of operations required to destroy the array and exterminate Lord Voldemort.

Input Format:
The first line contains a single integer n — the size of the array a (1<=n<=20).

The following line contains n integers a_1,a_2,ldots,a_n — array elements (-10^15<=a_i<=10^15).

Output Format:
Output a single integer — the minimum number of operations required to destroy the array a.

Note:
In the first example one can just apply the operation of the first kind three times.

In the second example, one can apply the operation of the second kind two times: first, choose i=2,j=1,x=4, it transforms the array into (0,-1,-2), and then choose i=3,j=2,x=-2 to destroy the array.

In the third example, there is nothing to be done, since the array is already destroyed.. Output only the code with no comments, explanation, or additional text.