n=int(input())
a=list(map(int,input().split()))
dp=[-1]*10
dp[0]=0
for x in a:
  x%=10
  ndp=[-1]*10
  for d in range(10):
    if dp[d]>=0:
      ndp[(d+x)%10]=dp[d]+1
  for d in range(10):
    dp[d]=max(dp[d],ndp[d])
print(dp[0])