public class No188 {
	public static void main(String[] args) {
		int happyday = 0;
		int day = 0;
		
		for(int i = 1;i <= 12;i++) {
			switch(i) {
				case 1:
				case 3:
				case 5:
				case 7:
				case 8:
				case 10:
				case 12: // 31日
					day = 31;
					break;
				case 4:
				case 6:
				case 9:
				case 11: // 30日
					day = 30;
					break;
				case 2: //28日
					day = 28;
					break;
			}
			for(int j = 1;j <= day;j++) {
				if((j / 10 + j % 10) == i) {
					//System.out.println(i + "月" + j + "日");
					happyday++;
				}
			}
		}
		
		System.out.println(happyday);
	}
}