import math

limit = 28123
numbers = set()

def abundant(n):
	divisors = set()
	divisors.add(1)
	for i in xrange(2, int(math.sqrt(n))+1):
		if n % i == 0:
			divisors.add(i)
			divisors.add(n/i)

	if sum(divisors) > n:
		return True
	else:
		return False

def sum_abundant(n):
	for i in numbers:
		if n-i in numbers:
			return True
	return False


for n in xrange(2, limit+1):
	if abundant(n):
		numbers.add(n)

sum = 0

for n in xrange(limit+1):
	if not sum_abundant(n):
		sum += n

print sum