Problem:
Score : 100 points

Problem Statement

Given is a string S representing the day of the week today.

S is SUN, MON, TUE, WED, THU, FRI, or SAT, for Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday, respectively.

After how many days is the next Sunday (tomorrow or later)?

Constraints

S is SUN, MON, TUE, WED, THU, FRI, or SAT.

Input

Input is given from Standard Input in the following format:

S

Output

Print the number of days before the next Sunday.

Sample Input 1

SAT

Sample Output 1

1

It is Saturday today, and tomorrow will be Sunday.

Sample Input 2

SUN

Sample Output 2

7

It is Sunday today, and seven days later, it will be Sunday again.

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

fn main() {
    let s: String = read_line_as_value();
    let ans = match &*s {
        "SUN" => 7,
        "MON" => 6,
        "TUE" => 5,
        "WED" => 4,
        "THU" => 3,
        "FRI" => 2,
        "SAT" => 1,
        _ => -1
    };
    println!("{}", ans);
}

fn read_line_as_value<T: std::str::FromStr>() -> T {
    let mut input = String::new();
    let res = std::io::stdin().read_line(&mut input);
    if let Err(error) = res {
        panic!("io error at stdin.read_line: {}", error);
    };
    match input.trim().parse() {
        Ok(val) => val,
        _ => panic!("error while parsing input: {}", input)
    }
}