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

dp = [[None]*10 for _ in range(N+1)]
dp[0][0] = 0
for i,a in enumerate(A):
    for d in range(10):
        dp[i+1][d] = dp[i][d]
    for d in range(10):
        if dp[i][d] is None: continue
        n = (d+a)%10
        dp[i+1][n] = max(0 if dp[i+1][n] is None else dp[i+1][n], dp[i][d] + 1)
print(dp[-1][0])