N=int(input())
A=list(map(int, input().split()))
B=[]
for i in A:
    B.append(i%10)
dp=[-100000]*10
dp[0]=0
for i in range(N):
    D=[-100000]*10
    for j in range(10):
        D[(j+B[i])%10]=max(dp[j]+1,dp[(j+B[i])%10])
    dp=D
print(dp[0])