n = int(input())
a = list(map(int, input().split()))
dp = [-10**6 for _ in range(10)]
dp[0] = 0
for x in a:
	x %= 10
	tmp = [-10**6 for _ in range(10)]
	for i in range(10):
		tmp[i] = max(dp[i], dp[(i-x)%10] + 1)
	dp = tmp
print(dp[0])