xs, ys = term.getSize()
input = ""
input2 = ""
test = ""
tempinput = ""

inputpart = 1
function cwrite(blah, y)
	local x = math.ceil(((xs/2)-(string.len(blah)/2)))
	term.setCursorPos(x,y)
	write(blah)
end

cmenu = num
sid = 0
function clear()
	term.clear()
	term.setCursorPos(1,1)
end

function menu(id, text, x, y)
	term.setCursorPos(x, y)
	print(text)
	if sid == id then
		term.setCursorPos(x,y)
		write">"
	else
		term.setCursorPos(x,y)
		write"*"
	end
end

while true do
	clear()
	cwrite("===================================",1)
	cwrite("=                                 =",2)
	cwrite(input .. test .. input2,2)
	cwrite("===================================",3)
	cwrite("=======================================",4)
	menu(0,"= 7 =", 6, 5)
	menu(1,"= 8 =", 10, 5)
	menu(2,"= 9 =", 14, 5)
	menu(3,"= 4 =", 6, 6)
	menu(4,"= 5 =", 10, 6)
	menu(5,"= 6 =", 14, 6)
	menu(6,"= 1 =", 6, 7)
	menu(7,"= 2 =", 10, 7)
	menu(8,"= 3 =", 14, 7)
	menu(9,"= - =", 6, 8)
	menu(10,"= 0 =", 10, 8)
	menu(11,"= . =", 14, 8)
	cwrite("=======================================",9)
	sleep(0)
	event, key = os.pullEvent("key")
	if key == 200 then
		if sid > 2 then
			sid = sid - 3
		end
	elseif key == 203 then
		if sid > 0 then
			sid = sid - 1
		end
	elseif key == 205 then
		if sid < 11 then
			sid = sid + 1
		end
	elseif key == 208 then
		if sid <= 11-3 then
			sid = sid + 3
		end
	elseif key == 29 then
		if cmenu == num then
			cmenu = action
		elseif cmenu == action then
			cmenu = num
		end
	end
		if key == 28 then
			if sid == 0 then
				tempinput = tempinput.."7"
			elseif sid == 1 then
				tempinput = tempinput.."8"
			elseif sid == 2 then
				tempinput = tempinput.."9"
			elseif sid == 3 then
				tempinput = tempinput.."4"
			elseif sid == 4 then
				tempinput = tempinput.."5"
			elseif sid == 5 then
				tempinput = tempinput.."6"
			elseif sid == 6 then
				tempinput = tempinput.."1"
			elseif sid == 7 then
				tempinput = tempinput.."2"
			elseif sid == 8 then
				tempinput = tempinput.."3"
			elseif sid == 9 then
				if input2 == "" then
					test = "-"
					inputpart = 2
					tempinput = ""
				else
					if test == "-" then
						answer = tonumber(input) - tonumber(input2)
						input2 = ""
						test = ""
						tempinput = answer
						inputpart = 1
					end
				end
			elseif sid == 10 then
				tempinput = tempinput.."0"
			elseif sid == 11 then
				tempinput = tempinput.."."
			end
		end


		if inputpart == 1 then
			input = tempinput
		else
			input2 = tempinput
		end
end