import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

num = 10 ** 5 + 1 #適当に値を入れる
L = [1 for i in range(num)]; L[0] = 0; L[1] = 0
plist = []
for i in range(num):
	if L[i] == 1:
		plist.append(i); c = 2
		while i * c <= num - 1:
			L[i * c] = 0; c += 1

#処理内容
def main():
	M = int(input())
	N = int(input())
	C = getlist()
	DP = [-INF] * (M + 1)
	DP[-1] = 0
	for i in range(M, -1, -1):
		for j in C:
			if i - j >= 0:
				DP[i - j] = max(DP[i - j], DP[i] + 1)

	ans = max(DP)
	# print(DP)
	for i in plist:
		if i <= M:
			if DP[i] != -INF:
				ans += DP[i]
		else:
			break

	print(ans)

if __name__ == '__main__':
	main()