#include <iostream>
using namespace std;
int main()
{
	int i,j,days;
	days = 0;
	for (i = 1; i <= 12; i++)
	{
		for (j = 1; j <= 30; j++)
		{
			if (i== (j / 10) + j-(j/10)*10)
			{
				days++;
			}
		}
	}
	cout << days << "\n";
	return 0;
}