#include <bits/stdc++.h>
using namespace std;

int main() { 
    int month, day;
    int lim;
    int ans;

    for (month = 1; month <= 12; month++) {
        if (month != 2 | month != 4 | month != 6 | month != 9 | month != 11) { 
            lim = 31;
        }
        else{
            lim = 30;
        } 
        for (day = 1; day <= lim; day++) {
            if (month == ((day / 10) + (day%10))) {
                ans += 1;
            } 
            else{
                cout << "\n";
            }
        }
    }

    cout << ans <<"\n";
    return 0;
}