#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max
#include <string>	//string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap
#include <cstdlib>	//abs(int)
#include <cmath>	//sqrt
#include <sstream>	//stringstream,getline

using namespace std;

int main() {

	int ans = 0;

	for (int i = 1; i <= 12; i++) {
		for (int j = 1; j <= 31; j++) {
			if (i == (j / 10) + (j % 10)) {
				ans++;
			}
		}
	}

	cout << ans - 1 << endl;

	return 0;

}