require 'prime'
n, l = gets.strip.split(' ').map(&:to_i)
d_max = l / (n - 1)
count = 0
if d_max >= 2
	count += l - 2 * (n - 1) + 1
end
i = 3
while i <= d_max
	count += l - i * (n - 1) + 1 if i.prime?

	i += 2
end
p count