n=int(input())
a=list(map(int,input().split()))
b=[]
for i in a:
    b.append(i%10)
dp=[[-1]*10 for _ in range(n+1)]
dp[0][0]=0
for i in range(1,n+1):
    num=b[i-1]
    for j in range(10):
        if dp[i-1][j]==-1:
            continue
        dp[i][j]=max(dp[i][j],dp[i-1][j])
        k=(j+num)%10
        dp[i][k]=max(dp[i][k],dp[i-1][j]+1)
print(dp[-1][0])