import java.util.*;

public class No491{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);

		long N = sc.nextLong();
		long tmp = (long)Math.pow(10, 9) + 1;
		if(N < tmp) System.out.println(0);
		else{
			long div = 1;
			long ans = 0;
			for(int digit = 1; digit < 10; digit++){
				for(int i = 1; i < 10; i++){
					if(N >= tmp*digitmul(digit, i)) ans++;
					else break;
	
				}
			}
			System.out.println(ans);
		}
		
	}
	private static long digitmul(long digit, long n){
		long v = 0;
		for(int i = 0; i < digit; i++){
			v += n*Math.pow(10, i);
		}
		return v; // return 11, 222, 5555, ...
	}
}