#yuki231
n=int(input())
a=list(map(int,input().split()))
l=[]
for i in a:
 l.append(i%10)
dp=[-100000]*10
dp[0]=0
for i in range(n):
 t=[-100000]*10
 for j in range(10):
  t[(j+l[i])%10]=max(dp[j]+1,dp[(j+l[i])%10])
 dp=t
print(dp[0])