Random terrain generater, Needhelp stopping it at a certain point Help?

Her is the script

 local height = 20
local size = 50
local y = 0
local x = 0
function HowmanyPlaced()
	place()
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end

function place()
	local inst = Instance.new("Part", game.Workspace)
	inst.Anchored = true
	inst.BrickColor = BrickColor.new("Forest green")
	inst.Position = Vector3.new(0,0,0)+ Vector3.new(y,0,x)
	inst.Size = Vector3.new(size,math.random(1,height),size)
	inst.Material = "Grass"
	y = y+size
	
end
while true do
	HowmanyPlaced()


x=x+size
y=0
wait(0.1)
end

i need help STOPPING it at a certain point in time this took me a while to figure out and i cant find out how