//---------------------------------------------------
// Purpose: Program to calculate magic numbers
// Author:  John Gauch
//---------------------------------------------------
#include <iostream>
using namespace std;

// Function to calculate magic number
int Magic(int Number)
{
   // Get digits and calculate sum
   int Sum = 0;
   while (Number > 0)
   {
      int Digit = Number % 10;
      Sum = Sum + Digit;
      Number = Number / 10;
   }
   return Sum;
}

// Main body of program
int main()
{
   // Get user input
   int Input, Output;
   cout << "Enter a positive integer: ";
   cin >> Input;

   // Do error checking
   if (Input < 0)
      cout << "Error: Number must be positive" << endl;

   // Calculate magic number and print results
   else
   {
      cout << "Input = " << Input << endl;
      Output = Magic(Input);
      cout << "Output = " << Output << endl;
      while (Output > 9)
      {
         Output = Magic(Output);
         cout << "Output = " << Output << endl;
      }
   }
   return 0;
}