const base: u64 = 1000000001;
fn main() {
    let mut line = String::new();
    std::io::stdin().read_line(&mut line);
    let n: u64 = line.trim().parse().unwrap();

    let mut mul = 1;
    let mut count = 0;
    'a: loop {
        for i in (1..10) {
            if mul * i * base > n {
                break 'a;
            }
            count += 1;
        }
        mul = mul * 10 + 1;
    }
    println!("{}", count);
}