write a go solution for Description:
You are given an array of n positive integers a_1,a_2,ldots,a_n.

In one operation you do the following:

1. Choose any integer x.
2. For all i such that a_i=x, do a_i:=0 (assign 0 to a_i).

Find the minimum number of operations required to sort the array in non-decreasing order.

Input Format:
Each test contains multiple test cases. The first line contains the number of test cases t (1<=t<=10^4). Description of the test cases follows.

The first line of each test case contains a single integer n (1<=n<=10^5).

The second line of each test case contains n positive integers a_1,a_2,ldots,a_n (1<=a_i<=n).

It is guaranteed that the sum of n over all test cases does not exceed 10^5.

Output Format:
For each test case print one integer — the minimum number of operations required to sort the array in non-decreasing order.

Note:
In the first test case, you can choose x=3 for the operation, the resulting array is [0,0,2].

In the second test case, you can choose x=1 for the first operation and x=3 for the second operation, the resulting array is [0,0,0,0].. Output only the code with no comments, explanation, or additional text.