N = int(input())
lsA = list(map(int,input().split()))
#すべてmod10とる
for i in range(N):
    lsA[i] = lsA[i]%10
#dp[i][j]=あまりｊにするための最大枚数
dp = [[-float('INF')]*10 for i in range(N+1)]
dp[0][0] = 0
for i in range(1,N+1):
    for j in range(10):
        dp[i][j] = max(dp[i-1][(j-lsA[i-1])%10]+1,dp[i-1][j])
print(dp[N][0])