N = 200000
isprime = [True] * N
isprime[0] = isprime[1] = False
for i in range(2, int(N ** 0.5 + 1)):
    if not isprime[i]:
        continue
    for j in range(i * i, N, i):
        isprime[j] = False

m = int(input())
n = int(input())
C = list(map(int, input().split()))
dp = [-1 << 30] * (m + 1)
dp[0] = 0
for c in C:
    for i in range(m - c + 1):
        dp[i + c] = max(dp[i + c], dp[i] + 1)
ans = max(dp)
for i in range(m + 1):
    if isprime[m - i]:
        ans += max(0, dp[i])
print(ans)