function createNewNumber ()
   math.randomseed(os.time())
   local numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9}
   local tNumb = {} -- list of numbers
   for i = 1, 4 do
      table.insert(tNumb, math.random(#tNumb+1), table.remove(numbers, math.random(#numbers)))
   end
   return tNumb
end

TNumber = createNewNumber ()
print ('(right number: ' .. table.concat (TNumber) .. ')')

function isValueInList (value, list)
   for i, v in ipairs (list) do
      if v == value then return true end
   end
   return false
end

local nGuesses = 0

while not GameOver do
   nGuesses = nGuesses + 1
   print("Enter your guess (or 'q' to quit): ")
   local input
   while not input do
      input = io.read()
   end
   if input == "q" then
      GameOver = true
      return
   end
   local tInput = {}
   for i=1, string.len(input) do
      local number = tonumber(string.sub(input,i,i))
      if number and not isValueInList (number, tInput) then
         table.insert (tInput, number)
      end
   end
   local malformed = false
   if not (string.len(input) == 4) or not (#tInput == 4) then
      print (nGuesses, 'bad input: too short or too long')
      malformed = true
   end

   if not malformed then
      print (nGuesses, 'parsed input:', table.concat(tInput, ', '))
      local nBulls, nCows = 0, 0
      for i, number in ipairs (tInput) do
         if TNumber[i] == number then
            nBulls = nBulls + 1
         elseif isValueInList (number, TNumber) then
            nCows = nCows + 1
         end
      end
      print (nGuesses, 'Bulls: '.. nBulls .. ' Cows: ' .. nCows)
      if nBulls == 4 then
         print (nGuesses, 'Win!')
         GameOver = true
      end
   end
end