proc put_zero_at_beginning( t is array[1..N] of int)

	variable i, i0 are int

	i = 1
	i0 = 1
	
	while i <= N and t[i] = 0 do
		i = i + 1
	end while
	
	while i <= N do
		if t[i] = 0 then
			swap t[i] with t[i0]
			i0 = i0 + 1
		end if
	end for

end proc