from collections import Counter
n = int(input())
a = list(map(int, input().split()))
t = [0] * 10
dp = [[-1] * 10 for _ in range(2)]
dp[0][0] = 0
for i in range(n):
    p, q = i % 2, (i + 1) % 2
    for k in range(10):
        if dp[p][k] >= 0:
            dp[q][(k + a[i]) % 10] = max(dp[q][(k + a[i]) % 10], dp[p][k] + 1)
        dp[q][k] = max(dp[q][k], dp[p][k])
print(max(dp[0][0], dp[1][0]))