/*********************************************************************/
/* Author: Suzanne Miller Dorney                                     */
/* File: lab2.c                                                      */
/* Class:  CPSC-202                                                  */
/* Project:  Lab 2                                                   */
/* Purpose:  This program will interactively perform a "MATH TRICK"  */
/*********************************************************************/
#include <stdio.h>

/* function prototype */
int SumOfDigits( int number );

int main( )
{
  int   number;       /* the current working number     */
  int   nines;        /* the next highest mult of 9     */

  /* Read in the initial number */
  printf( "Please enter a positive integer value: " );
  scanf( "%d", &number );

  number = number - SumOfDigits( number );

  printf( "Current number: %d\n", number );
  printf( "Please re-arrange the digits in the number: " );
  scanf( "%d", &number ); 

  number += 25;

  printf( "Current number: %d\n", number );
  printf( "Please remove any single non-zero digit and re-enter the number: " );
  scanf( "%d", &number ); 

  number = SumOfDigits( number );
  number -= 7;

  nines = number;
  while ( ( nines%9) != 0 )
    nines++;

  if ( nines == number )
    number = 9;
  else
    number = nines - number;

  printf( "The number you deleted was: %d\n", number );

  
  return 0;
}

/****************************************************************/
/* Function to determine the sum of the digits in an integer.   */
/*                                                              */
/* Input: sinlge integer value                                  */
/* Output: the sum of the digits in the input value             */
/****************************************************************/
int SumOfDigits( int number )
{
  int sum = 0;

  while ( abs( number ) > 0 )
  {
    sum += number % 10;
    number /= 10;
  }

  return sum;
}