proc main

   string sInput                    ;Input data string
   string sOutput                   ;Output string containing shifted data
   integer iLen, iCount, iValue

   strlen sInput iLen               ;Get length of string
   for iCount = 0 upto iLen-1       ;While data is left in string...
      strgetc sInput iCount iValue  ;Read a characters
      if iValue == 65               ;If character is an A
         iValue = 90                ;Convert to a Z
      elseif iValue == 97           ;If character is an a
         iValue = 122               ;Convert to a z
      else                          ;Otherwise shift character left
         iValue--
      endif
      strputc sOutput iCount iValue ;Write translated character to output string
   endfor
endproc