mod = 1000000007
eps = 10**-9
inf = 10**9


def main():
    import sys
    input = sys.stdin.readline

    N = int(input())
    A = list(map(int, input().split()))
    dp = [[-inf] * 10 for _ in range(N+1)]
    dp[0][0] = 0
    for i, a in enumerate(A):
        b = a % 10
        for j in range(10):
            dp[i+1][j] = max(dp[i+1][j], dp[i][j])
            dp[i+1][(j+b)%10] = max(dp[i+1][(j+b)%10], dp[i][j] + 1)
    print(dp[-1][0])


if __name__ == '__main__':
    main()