n = int(input())
A = list(map(int, input().split()))

INF = 10**10
DP = [[-INF for _ in range(10)] for _ in range(n + 1)]
DP[0][0] = 0
for i in range(n):
    for j in range(10):
        if DP[i][j] == -INF:
            continue
        DP[i + 1][j] = max(DP[i + 1][j], DP[i][j])
        r = (j + A[i]) % 10
        DP[i + 1][r] = max(DP[i + 1][r], DP[i][j] + 1)
print(DP[n][0])