N = int(input())
A = list(map(int,input().split()))
INF = 10**9
dp = [[-INF]*10 for _ in range(N+1)]
dp[0][0] = 0
for i in range(N):
    for j in range(N):
        dp[i+1][(j+A[i])%10] = max(dp[i][j]+1,dp[i+1][(j+A[i])%10])
        dp[i+1][j] = max(dp[i][j],dp[i+1][j])
print(dp[N][0])