fn main() {
    let mut n: usize = {
        let mut buf = String::new();
        std::io::stdin().read_line(&mut buf).unwrap();
        buf.trim_end().parse().unwrap()
    };

    let f = |mut n: usize| -> usize {
        let mut res = 0;
        while n > 0 {
            res += n % 10;
            n /= 10;
        }
        res
    };

    for _ in 0..99 {
        n = f(n);
    }
    println!("{}", n);
}