public class Main {
	public static void main(String[] args) {
		int result = 0;
		for (int i = 1; i <= 12; i++) {
			int day = 0;
			if (i == 2) {
				day = 28;
			} else if (i == 4 || i == 6 || i == 9 || i == 11) {
				day = 30;
			} else {
				day = 31;
			}
			for (int k = 1; k <= day; k++) {
				if (i == (k / 10) + (k % 10)) {
					result += 1;
				}
			}
		}
		System.out.println(result);
	}// mainmethod

} // class