B'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: 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. 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 a single integer -- the minimum number of operations required to destroy the array a . 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. '...