N = int(input())
A = [int(a) for a in input().split()]

for i in range(N):
    A[i] %= 10

dp = [[-1]*10 for _ in range(N+1)]
dp[0][0] = 0
for i in range(N):
    for j in range(10):
        if dp[i][j] == -1:
            dp[i+1][(j+A[i])%10] = dp[i][(j+A[i])%10]
        else:
            dp[i+1][(j+A[i])%10] = max(dp[i][(j+A[i])%10], dp[i][j]+1)

print(dp[N][0])