using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

public class Program{
  public static void Main(){
    List<int> days = Enumerable.Range(1,31).ToList<int>();
    List<int> _d = days.Select(s => GetDaySum(s)).ToList<int>();
    int overCount = _d.Count(c => 0 < c && c < 13);
    int outCount = 0;
    var _out = new List<Out>();
    _out.Add(new Out(2,29));
    _out.Add(new Out(2,30));
    _out.Add(new Out(2,31));
    _out.Add(new Out(4,31));
    _out.Add(new Out(6,31));
    _out.Add(new Out(9,31));
    _out.Add(new Out(11,31));
    foreach (var o in _out){
      if (o.Month == GetDaySum(o.Day)){
        outCount++;
      }
    }
    Console.WriteLine(overCount - outCount);
  }
  public static int GetDaySum(int d){
    if (d < 10) return d;
    return (d / 10) + (d % 10);
  }
}
public class Out{
    public int Month { get; set; }
    public int Day { get; set; }
    public Out(int m, int d){
        Month = m;
        Day = d;
    }
}