Count distinct elements

1 <= N <= 10^5
1 <= A[i] <= 10^9

First argument A is an array of integers.

Return an integer.

Input 1:
A = [3, 4, 3, 6, 6]

Input 2:
A = [3, 3, 3, 9, 0, 1, 0]

Output 1:
3

Output 2:
4

Explanation 1:
The distinct elements of the array are 3, 4 and 6.

Explanation 2:
The distinct elements of the array are 3, 9, 0 and 1.