local dictionary = {}

local function insertWord(dict, word)
	local head, tail = word:upper():match('^(%a)(%a*)$')
	if not head then return false; end
	if not dict[head] then dict[head] = {}; end
	if tail == '' then
		dict[head][''] = true
		return true
	else
		return insertWord(dict[head], tail)
	end
end

local function confirmWord(dict, word)
end

insertWord(dictionary, 'BAG')

print(confirmWord(dictionary, 'BAG'))