N = int(input())
A = list(map(int,input().split()))
inf = -(1 << 30)
dp = [[inf] * 10 for _ in range(N)]
dp[0][0] = 0
dp[0][A[0]%10] = 1
for i in range(N-1):
    for j in range(10):
        dp[i+1][(j+A[i+1])%10] = max(dp[i+1][(j+A[i+1])%10],dp[i][j] + 1)
    for j in range(10):
        dp[i+1][j] = max(dp[i+1][j],dp[i][j])
print(dp[-1][0])