import java.util.Arrays;
import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		new Main().run();
	}

	static long N;
	static long FACTOR = 1_000_000_000 + 1;
	static long[] pow10 = new long[19];

	void run() {
		pow10[0] = 1;
		for (int i = 1; i < pow10.length; ++i)
			pow10[i] = pow10[i - 1] * 10;

		Scanner sc = new Scanner(System.in);
		N = sc.nextLong();
		long ans = 0;
		for (int i = 0; i <= 8; ++i) {
			ans += dfs(0, i, 0, true);
		}
		System.out.println(ans);
	}

	static long dfs(int s, int t, long cur, boolean f) {
		if (s > t) {
			if (cur > 0) {
				return 1;
			} else
				return 0;
		}
		long sum = 0;
		for (int i = (f ? 1 : 0); i < 10; ++i) {
			long tmp = cur + (pow10[s] + (s == t ? 0 : pow10[t])) * i;
			if (tmp * FACTOR <= N) {
				sum += dfs(s + 1, t - 1, tmp, false);
			}
		}
		return sum;
	}

	static void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

}