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Get num from user
Validate value of num (0 <= num <= 27)

Vary 1 digit at a time from the digit sequence 000 to the digit 
  sequence 999
    If the sum of the digits is equal to num, print the 3 digits  
      (or less) with no space between them.  Don’t print leading 
      0’s.
    Increment the counter.

Print the count

  

/**************************************************************
 * Filename:       first.c                                    *
 * Name:           Ima Student                                *
 * SSAN:           6789                                       *
 * Date:           3 October 2000                             *
 * Course:         CMSC-104                                   *
 * Description:    (Your psuedocode goes here)                *
 * Notes:          (As needed, such has how to compile)       *
 **************************************************************/