N = int(input())
a = list(map(int, input().split()))
for i in range(N):
    a[i] = a[i] % 10
dp = [-1] * 10
dp[0] = 0
for i in range(N):
    cdp = dp[:]
    for j in range(10):
        if cdp[j] != -1:
            dp[(j + a[i]) % 10] = max(dp[(j + a[i]) % 10], cdp[j] + 1)
        dp[j] = max(dp[j], cdp[j])

print(dp[0])