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

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 n = io.read("*n")
local t = {}
for i = 1, n do
  local a = io.read("*n")
  t[a] = true
end
local primes = getprimes(5100000)
local lim = 5000000
local ret = -1
local left = 1
local curuse, curcnt = {}, 0
for i = 1, #primes do
  local p = primes[i]
  if lim < p then break end
  local valid = true
  while 0 < p do
    local v = p % 10
    if not t[v] then
      valid = false
      break
    else
      if not curuse[v] then
        curuse[v] = true
        curcnt = curcnt + 1
      end
    end
    p = mfl(p / 10)
  end
  if not valid then
    curuse = {}
    curcnt = 0
    left = primes[i] + 1
  elseif curcnt == n then
    local right = primes[i + 1] - 1
    right = mmi(right, lim)
    ret = mma(ret, right - left)
  end
end
print(ret)