N = int(input())
A = list(map(int, input().split()))
inf = 10 ** 18
pre = [-inf] * 10
pre[0] = 0
for i in range(N):
    dp = [-inf] * 10
    for j in range(10):
        dp[j] = max(dp[j], pre[j])
        dp[(j + A[i])%10] = max(dp[(j + A[i])%10], pre[j] + 1)
    dp, pre = pre, dp
print(pre[0])