n=int(input())
ns=list(map(int,input().split()))

dp=[[-1]*10 for i 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]=max(dp[i][j],dp[i+1][j])
        dp[i+1][(j+ns[i])%10] = max(dp[i][j]+1,dp[i+1][(j+ns[i])%10])

    
print(dp[-1][0])