N, *A = map(int, open(0).read().split())

dp = [-1] * 10
dp[0] = 0
for a in A:
    t = [-1] * 10
    for i in range(10):
        if dp[i] == -1:
            continue
        t[i] = max(t[i], dp[i])
        n = (i + a) % 10
        t[n] = max(t[n], dp[i] + 1)
    dp = t
print(dp[0])