n = int(input())
a = list(map(int, input().split()))
INF = 10 ** 10


for i in range(n):
    a[i] = a[i] % 10

dp = [[-INF] * 10 for i in range(n + 1)]
dp[0][0] = 0

for i in range(n):
    for j in range(10):
        dp[i + 1][j] = max(dp[i][(j - a[i]) % 10] + 1, dp[i + 1][j], dp[i][j])

print(dp[-1][0])