isPrime = function(n)
	if n <= 3 then return n > 1
	if n % 2 == 0 or n % 3 == 0 then return false
	
	i = 5
	while i ^ 2 <= n
		if n % i == 0 or n % (i + 2) == 0 then return false
		i += 6
	end while
	return true
end function

digitSum = function(n)
	sum = 0
	while n > 0
		sum += n % 10
		n = floor(n / 10)
	end while
	return sum
end function

additive = []

for i in range(2, 500)
	if isPrime(i) and isPrime(digitSum(i)) then additive.push(i)
end for
print "There are " + additive.len + " additive primes under 500."
print additive