import sys
input = sys.stdin.readline

N = int(input())
A = list(map(int, input().split()))
dp = [[-10**18]*10 for _ in range(N+1)]
dp[0][0] = 0

for i in range(N):
    for j in range(10):
        dp[i+1][j] = max(dp[i+1][j], dp[i][j])
        dp[i+1][(j+A[i])%10] = max(dp[i+1][(j+A[i])%10], dp[i][j]+1)

print(dp[N][0])