import sys
input=sys.stdin.readline
def I(): return int(input())
def MI(): return map(int, input().split())
def LI(): return list(map(int, input().split()))

def main():
    mod=10**9+7
    
    N=I()
    A=LI()
    for i in range(N):
        A[i]%=10
        
    dp=[[-1]*10 for _ in range(N+1)]
    # dp[i][j]はi枚見て，1の位がjの時の最大枚数
    
    dp[0][0]=0
    
    for i in range(N):
        a=A[i]
        for j in range(10):
            if dp[i][j]!=-1:
                dp[i+1][j]=max(dp[i+1][j],
                               dp[i][j])
                dp[i+1][(j+a)%10]=max(dp[i+1][(j+a)%10],
                                      dp[i][j]+1)

            
    ans=dp[-1][0]
    print(ans)
    


main()