source_code: import java.util.Scanner;
  
  public class Main
  {
  
      public static void main(String[] args)
      {
          setup();
          xuly();
      }
  
      private static long dp[][] = new long[20][170];
  
      private static void setup() {
          dp[0][0] = 1;
          for (int i = 1; i < 20; i ++)
              for (int j = 0; j < 170; j ++)
                  for (int k = Math.max(j - 9, 0); k <= j; k ++)
                      dp[i][j] += dp[i - 1][k];
      }
  
      private static int sumD(long x) {
          int ret = 0;
          while(x > 0) {
              ret += x % 10;
              x /= 10;
          }
          return ret;
      }
  
      private static long numSatisfy(long limit, int sumDigit) {
          long ret = 0;
          int curSum = sumD(limit);
          if (curSum == sumDigit)
              ret ++;
  
          for (int i = 0; i < 20; i ++) {
              int bound = (int) (limit % 10);
              curSum -= bound;
              for (int d = 0; d < bound && curSum + d <= sumDigit; d ++)
                  ret += dp[i][sumDigit - curSum - d];
              limit /= 10;
          }
  
          return ret;
      }
  
      private static void xuly() {
          Scanner scanner = new Scanner(System.in);
          long n = scanner.nextLong();
          long s = scanner.nextLong();
          long ans = 0;
          for (int sum = 1; sum < 170; sum ++)
              if (n >= s + sum)
                  ans += numSatisfy(n, sum) - numSatisfy(s + sum - 1, sum);
          System.out.print(ans);
      }
  }
  