n = int(input())
A = list(map(int, input().split()))
INF = 10**18
dp = [[-INF]*10 for _ in range(n+1)]
dp[0][0] = 0
for i in range(n):
    a = A[i]
    for j in range(10):
        dp[i+1][j] = dp[i][j]
    for j in range(10):
        k = (j+a)%10
        dp[i+1][k] = max(dp[i+1][k], dp[i][j]+1)
print(dp[-1][0])