import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        char[] arr = sc.next().toCharArray();
        int length = arr.length;
        if (length > 2) {
            int[][] dp = new int[length + 1][2];
            dp[0][0] = 1;
            for (int i = 1; i <= length; i++) {
                int a = arr[i - 1] - '0';
                if (a % 3 == 0) {
                    dp[i][0] += dp[i - 1][0];
                    
                }
                dp[i][1] += dp[i - 1][0] * ((a + 2) / 3);
                dp[i][1] += dp[i - 1][1] * 4;
            }
            int count = dp[length][0] + dp[length][1] - 4;
            for (int i = 10; i <= 99; i++) {
                if (i % 10 % 3 != 0 && (i % 10 + i / 10) % 3 == 0) {
                    count++;
                }
            }
            System.out.println(count);
        } else {
            int count = 0;
            for (int i = 10; i <= Integer.parseInt(new String(arr)); i++) {
                if ((i % 10 + i / 10) % 3 == 0) {
                    count++;
                }
            }
            System.out.println(count);
        }
    }
}