Problem:
Score : 300 points

Problem Statement

You drew lottery N times. In the i-th draw, you got an item of the kind represented by a string S_i.

How many kinds of items did you get?

Constraints

1 \leq N \leq 2\times 10^5

S_i consists of lowercase English letters and has a length between 1 and 10 (inclusive).

Input

Input is given from Standard Input in the following format:

N
S_1
:
S_N

Output

Print the number of kinds of items you got.

Sample Input 1

3
apple
orange
apple

Sample Output 1

2

You got two kinds of items: apple and orange.

Sample Input 2

5
grape
grape
grape
grape
grape

Sample Output 2

1

Sample Input 3

4
aaaa
a
aaa
aa

Sample Output 3

4

Solution in OCaml (4.10.0) (judge verdict: Accepted)

let n = read_int()

module SS = Set.Make(String)

let rec f i ans set =
  if i = n then ans
  else
    let s = read_line () in
    if SS.mem s set then f (i + 1) ans set
    else f (i + 1) (ans + 1) (SS.add s set)

let () = print_int (f 0 0 SS.empty)