# 部分和dpの変形かな
# dp[i番目まで見て][j mod 10]の最高枚数
# aはmod 10する

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

INF = 10**20
dp = [[-INF]*10 for i in range(N+1)]
dp[0][0] = 0

for i in range(1, N+1):
    num = A[i-1]%10
    # 使わない
    for j in range(10):
        dp[i][j] = dp[i-1][j]
    # 使う
    for j in range(10):
        dp[i][(j+num)%10] = max(dp[i][(j+num)%10], dp[i-1][j]+1)
        
    #print(dp[i])
    
ans = dp[N][0]
print(ans)