Given an array of $n$ integers, count the number of subsets whose elements' product is a square number.
Also count the empty subset with product equal to one.
The first line has an integer $n$ : the size of the array.
The next line has $n$ integers $x_1, x_2,\dots, x_n$ : the contents of the array.
Print one integer: the answer to the problem modulo $10^9 + 7$ .