function scan()
  while true do
    a[1..n] := collect;
    b[1..n] := collect;
    if (∀j∈{1, ..., n}) (a[j].ver = b[j].ver) then
      return (b[1].data, ..., b[n].data)
  end
end function

function update(i,v)
   M[i] := v;
end