local mce, mfl, msq, mmi, mma = math.ceil, math.floor, math.sqrt, math.min, math.max

local function getprimes(x)
  local primes = {}
  local allnums = {}
  for i = 1, x do allnums[i] = true end
  for i = 2, x do
    if(allnums[i]) then
      table.insert(primes, i)
      local lim = mfl(x / i)
      for j = 2, lim do
        allnums[j * i] = false
      end
    end
  end
  return primes
end

local m = io.read("*n")
local n = io.read("*n")
local c = {}
for i = 1, n do c[i] = io.read("*n") end
local primes = getprimes(m)

local t0 = -1
local t = {}
for i = 1, m - 1 do t[i] = -1 end
t[m] = 0
for i_c = 1, n do
  local cost = c[i_c]
  for i_t = 1, m do
    if 0 <= t[i_t] then
      local cnt = t[i_t]
      local t_tmp = i_t
      while cost <= t_tmp do
        cnt = cnt + 1
        if cost == t_tmp then
          if t0 == -1 then
            t0 = cnt
          else
            t0 = mma(t0, cnt)
          end
        else
          if t[t_tmp - cost] == -1 then
            t[t_tmp - cost] = cnt
          else
            t[t_tmp - cost] = mma(t[t_tmp - cost], cnt)
          end
        end
        t_tmp = t_tmp - cost
      end -- while cost <= t_tmp
    end -- 0 <= t[i_t]
  end -- for i_t
end -- for i_c
local normmax = t0
for i = 1, m do
  normmax = mma(normmax, t[i])
end
local primecost = 0
for i = 1, #primes do
  if 0 < t[primes[i]] then
    primecost = primecost + t[primes[i]]
  end
end
print(normmax + primecost)