use std::io::{self, Write};

fn calc_age(age: u16) -> u16 {
    const DAYS_IN_YEAR: u16 = 365;
    return age * DAYS_IN_YEAR;
}

fn main() {
    print!("Write your age: ");
    io::stdout().flush().expect("Failed to flush stdout.");

    let mut buffer = String::new();
    io::stdin()
        .read_line(&mut buffer)
        .expect("Error while trying to read from stdin.");

    let age: u16 = buffer.trim().parse()
        .expect("The input is not an integer between 0 and 65535");
    
    let days = calc_age(age);
    println!("Your age is about {} days", days);
}