from collections import defaultdict
n = int(input())
a = list(map(int, input().split()))
dp = [[0]*10 for i in range(n+1)]

for i in range(n):
    dp[i+1][a[i]%10] += 1
    for g in range(10):
        dp[i+1][g%10] = max(dp[i][g], dp[i+1][g%10])
        if dp[i][g] != 0:
            dp[i+1][(g+a[i])%10] = max(dp[i][g]+1, dp[i+1][(g+a[i])%10])

print(dp[n][0])