n = int(input())
*a, = map(int,input().split())
dp = [0]+[-1<<30]*9
for ai in a:
    ndp = dp[:]
    for i in range(10):
        v = (i+ai)%10
        ndp[v] = max(ndp[v],dp[i]+1)
    dp = ndp
print(dp[0])