N = int(input())
A = list(map(int,input().split()))
ans = 0

dp = [[-1 for _ in range(10)] for _ in range(N+1)]
dp[0][0] = 0

for i in range(N):
  for j in range(10):
    if dp[i][j] == -1:
      continue
    dp[i+1][(j+A[i])%10] = max(dp[i+1][(j+A[i])%10], dp[i][j]+1)
    dp[i+1][j] = max(dp[i+1][j], dp[i][j])
print(dp[N][0])