N = int(input())
A = list(map(int, input().split()))

# dp[mod] = 最大の枚数
dp = [-1] * 10
dp[0] = 0
for a in A:
    dp_tmp = [-1] * 10
    for i in range(10):
        if dp[i] == -1:
            continue
        dp_tmp[i] = max(dp[i], dp_tmp[i])
        n = (i + a) % 10
        dp_tmp[n] = max(dp[i] + 1, dp_tmp[n])
    dp = dp_tmp

print(dp[0])