#include <iostream>
using namespace std;

int main()
{
    int ans = 0;
    for (int month = 1; month <= 12; month++)
    {
        for (int day = 1; day <= 31; day++)
        {
            if ((day / 10 + day % 10) == month)
            {
                ans++;
            }
        }
    }
    // 4/31の分を引く
    cout << ans - 1 << endl;
    return 0;
}