use std::io::*;
use std::str::FromStr;
//use std::num;
//use std::cmp;

fn main() {
    let mut count = 0;
    for _i in 1..=12{
        for _j in 1..=30{
            if _i == _j / 10 + _j % 10{
                count += 1;
            }
        }
    }
    println!("{}",count);
}

pub fn read_line() -> String {
    let mut s: String = String::new();
    std::io::stdin().read_line(&mut s).ok();

    s
}

pub fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

pub fn read_array() -> Vec<char> {
    let array: String = read();
    let chars: Vec<char> = array.trim().chars().collect::<Vec<char>>();
    chars
}

pub fn get_data() -> Vec<u64> {
    let mut s: String = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let vec: Vec<u64> = s
        .trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect();

    vec
}

pub fn get_chars() -> Vec<char> {
    let mut s: String = String::new();
    std::io::stdin().read_line(&mut s).ok();

    let vec: Vec<char> = s.trim().chars().collect::<Vec<char>>();

    vec
}