Problem:
Score : 100 points

Problem Statement

In some other world, today is December D-th.

Write a program that prints Christmas if D = 25, Christmas Eve if D = 24, Christmas Eve Eve if D = 23 and Christmas Eve Eve Eve if D = 22.

Constraints

22 \leq D \leq 25

D is an integer.

Input

Input is given from Standard Input in the following format:

D

Output

Print the specified string (case-sensitive).

Sample Input 1

25

Sample Output 1

Christmas

Sample Input 2

22

Sample Output 2

Christmas Eve Eve Eve

Be sure to print spaces between the words.

Solution in Rust (1.15.1) (judge verdict: Accepted)

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

fn main() {
    input!{
        d: usize
    }
    println!("{}", match d {
        25 => "Christmas".to_string(),
        24 => "Christmas Eve".to_string(),
        23 => "Christmas Eve Eve".to_string(),
        22 => "Christmas Eve Eve Eve".to_string(),
        _ => unreachable!()
    });
}