N=int(input())
DP=[[-N]*10 for i in range(N+1)]
DP[0][0]=0
A=list(map(int,input().split()))
for i in range(N):
  A[i]%=10
  for j in range(10):
    DP[i+1][j]=max(DP[i+1][j],DP[i][j])
    DP[i+1][(j+A[i])%10]=max(DP[i+1][(j+A[i])%10],DP[i][j]+1)
print(DP[N][0])