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

dp = [-float("INF")]*10
dp[0] = 0
for i in range(n):
    x = a[i]%10
    ndp = [-float("INF")]*10
    for j in range(10):
       ndp[(j+x)%10] = max(dp[j]+1,dp[(j+x)%10])
    dp = ndp
print(dp[0])