N=int(input())
A=["*"]+list(map(int,input().split()))

inf=float("inf")
DP=[[-inf]*10 for _ in range(N+1)]
DP[0][0]=0

for i in range(1,N+1):
    a=A[i]%10
    for m in range(10):
        DP[i][m]=max(DP[i-1][m],DP[i-1][(m-a)%10]+1)
print(DP[N][0])