#include <iostream>
using namespace std;

int main(void){
    int m, d, i = 0, count = 0;

    for(m=1; m<=12; m++){
        if(m == 2) d = 28;
        else if(m == 4 || m == 6 || m == 9 || m == 11) d = 30;
        else d = 31;
        for(i=1; i<=d; i++)
            if(m == i/10 + i%10) count++;
    }
    cout << count << endl;

    return 0;
}