#include<iostream>
#include<algorithm>
#include <vector>
#include<cmath>
#include<iomanip>
using namespace std;
typedef long long int lont;
int main() {
	int cnta = 1;
	for (int ia = 1; ia <= 12; ia++) {
		for (int ib = 1; ib <= 31; ib++) {
			if (ia == ib / 10 + ib % 10) {
				cnta++;
			}
		}
	}
	cout << cnta << endl;
}