while line = gets
  count = 0;
  n, x = line.split.map(&:to_i)
  if n == 0 then break end
  for i in 1..n do
    for j in (i + 1)..n do
      for k in (j + 1)..n do
        if (i + j + k) == x then count += 1 end
      end
    end
  end
  puts count
end