def eratosthenes(n : Int32)
  res = [true] * (n + 1)
  res[0] = res[1] = false
  2.to(n) do |i|
    next if !res[i] || i.to_i64 ** 2 > n
    (i**2).step(to: n, by: i) do |j|
      res[j] = false
    end
  end
  res
end

def primes(n : Int32)
  flag = eratosthenes(n)
  (2..n).select { |i| flag[i] }
end

m = read_line.to_i
n = read_line.to_i
c = read_line.split.map &.to_i

dp = [-1] * (m + 1)
dp[m] = 0
m.to(0) do |i|
  next if dp[i] == -1
  c.each do |cost|
    dp[i - cost] = {dp[i - cost], dp[i] + 1}.max if i - cost >= 0
  end
end

ans = dp.max
prime = eratosthenes(m)
m.to(0) do |i|
  ans += dp[i] if prime[i] && dp[i] != -1
end
puts ans