Counting Unique Items in Inventory

You are given a list of n integers which represent the IDs of items in an inventory. Your task is to determine the number of unique item IDs in the list.

If the list is empty (i.e. n = 0), then the output should be 0.

Input Format: The input is read from standard input where the first line contains an integer n. The second line contains n space-separated integers representing the inventory items.

Output Format: Print a single integer denoting the total count of distinct item IDs.

Constraints:

• 0 ≤ n ≤ 10⁵
• The item IDs are integers.

Example

If the input is: 7 on the first line and 1 2 2 3 3 3 4 on the second line, then the output should be: 4, since there are 4 unique items: 1, 2, 3, and 4.

inputFormat

The first line of input contains an integer n — the number of items in the inventory list. The second line contains n space-separated integers representing the item IDs.

outputFormat

Output a single integer — the count of distinct item IDs in the input list.

## sample

1
2

1

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