# Perfect numbering : give new free identifiers
	# ids : identifiers to hash (super-classes)
	# n : number of required free identifiers
	# idc : This array will be filled with n free identifiers
	# return the size of hashTable to create for theses identifiers (mask + 1)
	#
	#     var ph = new Perfecthashing
	#     var idc = new Array[Int]
	#     assert ph.pnand([3, 7, 10], 1, idc) == 6
	#     assert idc[0] == 4
	#     var idc1 = new Array[Int]
	#     assert ph.pnand([3, 7, 10], 1, idc1) == 6
	#     assert idc1[0] == 6
	fun pnand(ids: Array[Int], n: Int, idc: Array[Int]): Int
	do
		var mask = phand(ids) -1
		var i = 0
		while n+ids.length > (1 << mask.number_bits(1)) do
			# When there are not enough 1-bits
			if mask.getbit(i) == 0 then
				mask = mask ^ (1 << i)
			end
			i += 1
		end

		# Resetting hashtable
		for j in [0..(mask+1)] do tempht[j] = null

		# Set the temporary hashtable for `compute_least_free_ids`
		phandp(ids, mask)

		# Fill the given array with n free identifiers
		compute_least_free_ids(n, mask, idc)

		return mask + 1
	end