Counting Unique Items

You are given a list of items represented as strings. Your task is to count the number of unique items in the list. Two items are considered the same if and only if their strings are exactly equal.

Formally, given a list of items \(commands = [s_1, s_2, \ldots, s_n]\), you are to compute \(\left|\{ s_i : 1 \leq i \leq n \}\right|\), the size of the set of items.

inputFormat

The first line of input contains a single integer \(n\) (\(0 \le n \le 10^5\)) representing the number of items. Each of the next \(n\) lines contains a string which represents an item.

If \(n = 0\), then there are no item lines following.

outputFormat

Output a single integer which is the number of unique items in the list.

## sample

5
itemA
itemB
itemA
itemC
itemB

3

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