Problem:
Score : 200 points

Problem Statement

An X-layered kagami mochi (X ≥ 1) is a pile of X round mochi (rice cake) stacked vertically where each mochi (except the bottom one) has a smaller diameter than that of the mochi directly below it. For example, if you stack three mochi with diameters of 10, 8 and 6 centimeters from bottom to top in this order, you have a 3-layered kagami mochi; if you put just one mochi, you have a 1-layered kagami mochi.

Lunlun the dachshund has N round mochi, and the diameter of the i-th mochi is d_i centimeters. When we make a kagami mochi using some or all of them, at most how many layers can our kagami mochi have?

Constraints

1 ≤ N ≤ 100

1 ≤ d_i ≤ 100

All input values are integers.

Input

Input is given from Standard Input in the following format:

N
d_1
:
d_N

Output

Print the maximum number of layers in a kagami mochi that can be made.

Sample Input 1

4
10
8
8
6

Sample Output 1

3

If we stack the mochi with diameters of 10, 8 and 6 centimeters from bottom to top in this order, we have a 3-layered kagami mochi, which is the maximum number of layers.

Sample Input 2

3
15
15
15

Sample Output 2

1

When all the mochi have the same diameter, we can only have a 1-layered kagami mochi.

Sample Input 3

7
50
30
50
100
50
80
30

Sample Output 3

4

Solution in Rust (1.42.0) (judge verdict: Accepted)

use std::io::prelude::*;
use std::str::FromStr;
pub struct Scanner<R: Read>(R);
impl<R: Read> Scanner<R> {
    pub fn new(reader: R) -> Self {
        Self(reader)
    }
    pub fn read<T: FromStr>(&mut self) -> T {
        let token = self
            .0
            .by_ref()
            .bytes()
            .map(|b| b.unwrap())
            .skip_while(|&b| (b as char).is_whitespace())
            .take_while(|&b| !(b as char).is_whitespace())
            .collect::<Vec<u8>>();
        unsafe { std::str::from_utf8_unchecked(token.as_slice()) }
            .parse()
            .ok()
            .expect("Can't parse it.")
    }
    pub fn vec<T: FromStr>(&mut self, n: usize) -> Vec<T> {
        (0..n).map(|_| self.read()).collect()
    }
    pub fn chars(&mut self) -> Vec<char> {
        self.read::<String>().chars().collect()
    }
}
fn main() {
    let (stdin, stdout) = (std::io::stdin(), std::io::stdout());
    let mut sc = Scanner::new(stdin.lock());
    let mut out = std::io::BufWriter::new(stdout.lock());
    solve(&mut sc, &mut out);
    out.flush().ok().unwrap();
}
fn solve(sc: &mut Scanner<std::io::StdinLock>, out: &mut std::io::BufWriter<std::io::StdoutLock>) {
    let N: usize = sc.read();
    let A: Vec<i32> = sc.vec(N);

    use std::collections::HashMap;
    let mut map: HashMap<i32, bool> = HashMap::new();

    for a in A.iter() {
        let _ = map.entry(*a).or_insert(true);
    }
    println!("{}", map.len());
}