How do I check if a player is not in the region anymore without using "else" because it won't work?

I would make a table storing players that got in the Region, and when you don't find those players anymore, it means that they left

local region = Region3.new(Vector3.new(0,0,0), Vector3.new(182.25, 67, 101.75))

local player = game:GetService("Players")

local PlayersTable = {}
local TempPlayers = {}

local part = Instance.new("Part")
part.Anchored = true
part.Size = region.Size
part.Position = part.Position + Vector3.new(8.375, 24.25, 42.875)
part.Parent = game.Workspace
part.CanCollide = false
part.Transparency = 0.5

while wait() do
    local partsInRegion = workspace:GetPartsInPart(part)
    for i, part in pairs(partsInRegion) do
        if part.Parent:FindFirstChild("Humanoid") and not table.find(TempPlayers, part.Parent) then
            if not table.find(PlayersTable, part.Parent) then
                print(part.Parent.Name .. " got inside")
                table.insert(PlayersTable, part.Parent)
            end
            table.insert(TempPlayers, part.Parent) -- no matter if it's new or old, you add to this table
        end
    end
    -- to check if someone left you go over Players table and check if there are players that are no longer in TempPlayers
    for i, plr in pairs(PlayersTable) do
        if not table.find(TempPlayers, plr) then
            print(plr.Name .. " left")
            table.remove(PlayersTable, i) -- remove this player from players table because it's no longer inside the region
        end
    end
    table.clear(TempPlayers) -- clear so you can check again
end

try this script, I didn't test it but it should theoretically work, if something is wrong tell me and i'll try to fix it