#include <iostream>
using namespace std;

int main() {
    int counthappyday=-1, sum=0;
    for(int month=1; month<=12; month++){
        for(int day=1; day<=31; day++){
            int a = day/10;
            int b = (day%10);
            if(a+b==month){
                counthappyday++;
            }
        }
    }
    cout << counthappyday << endl;
    return 0;
}