import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		int count = 0;
		for (int i=1; i<=12; i++) {
			if (i==2) { //-28
				for (int j=1; j<=28; j++) {
					int temp = 0;
					if (j>=10) {
						temp = j/10 + j%10;
					}
					else {
						temp = j;
					}
					if (i==temp) {count++;}
				}
			}
			else if (i==4 || i==6 || i==9 || i==11) { //-30
				for (int j=1; j<=30; j++) {
					int temp = 0;
					if (j>=10) {
						temp = j/10 + j%10;
					}
					else {
						temp = j;
					}
					if (i==temp) {count++;}
				}
			}
			else { //-31
				for (int j=1; j<=31; j++) {
					int temp = 0;
					if (j>=10) {
						temp = j/10 + j%10;
					}
					else {
						temp = j;
					}
					if (i==temp) {count++;}
				}
			}
		}
		System.out.println(count);
	}
}