too long without yielding

yes=true
no=false
lock="lock"
unlock="unlock"
pass="admin"
monstat=""
Currentstate=""
Logged = false

Lokit = function(bool,state,Cstate)
 redstone.setOutput("back", bool)
 redstone.setOutput("bottom", bool)
 monstat = state
 Currentstate = Cstate
end

Lokit(yes,"Locked","Locked")
mon = peripheral.wrap("top")

while true do
mon.clear()
mon.setCursorPos(1,1)
mon.write(monstat)
term.clear()
term.setCursorPos(1,1)
 if Logged then
  print("Lockdown system activated!")
  print("status: "..Currentstate)
  input = read()
  if input == lock then
   Lokit(yes,"Locked","Locked")
   print("Area now on Lockdown!")
   sleep(1)
  elseif input == unlock then
   Lokit(no,"UNL","Unlocked")
   write("Area Unlocked, watch your back!")
   sleep(1)
  elseif input == "logout" then Logged=false
 end
 if not Logged then
  print ("Please enter the master password!")
  input = read("*")
  if input == pass then Logged = true
  end
 end
end
end