a = []
n = int(input())
i = 0
while i < n:
	b = int(input())
	a.append(b)
	i = i+1
i =0
c = 0
n = len(a)
while i < n:
	if a[i] % 3 == 0:
		c = c + a[i]
	i = i + 1
print(c)