dp = [-1] * 10
dp[0] = 0
input()
for a in map(int, input().split()):
    ndp = dp[:]
    for i in range(10):
        if dp[i] < 0:
            continue
        j = (i + a) % 10
        ndp[j] = max(ndp[j], dp[i] + 1)
    dp = ndp
print(dp[0])