how can i make the level bar not overflow?

local XP = game.Players.LocalPlayer.leaderstats.PunchExp
local levelbar = script.Parent

XP.Changed:Connect(function()
    local XP = game.Players.LocalPlayer.leaderstats.PunchExp


    local a = ( XP.Value /  100)
print(game.ReplicatedStorage.Dmg.Value * 100)
    levelbar:TweenSize(UDim2.new(a,0,1,0),"Out","Quad",.25)
end)