#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <iomanip>
#include <cctype>
using namespace std;
typedef long long ll;

int main()
{
	int sum = 0;
	for (int i = 1; i <= 12; i++)
	{
		int a;
		if (i == 2)a = 28;
		else if ((i == 4) || (i == 6) || (i == 9) || (i == 11))a = 30;
		else a = 31;
		for (int j = 1; j <= a; j++)
		{
			if (i == j / 10 + j % 10)sum++;
		}
	}
	cout << sum << endl;
	return 0;
}