import sys


def input(): return sys.stdin.readline().rstrip('\n')


def main():
    dp = [0] + [float('-inf')] * 9
    input()
    *a, = map(int,input().split())
    for v in a:
        rdp = dp[:]
        for i in range(10):
            rdp[(i + v) % 10] = max(rdp[(i + v) % 10], dp[i] + 1)
        dp = rdp
    print(dp[0])


if __name__ == '__main__':
    ret = main()
    if ret is not None:
        print(ret)