require "prime"
require "set"
prime_max = 5000000

gets
set = gets.split.map(&:to_i).to_set

ok_set = Set.new
start = 1
now_set = Set.new

Prime.each(prime_max) do |prime|
  num_set = prime.to_s.each_char.map(&:to_i).uniq.to_set
  if set.superset?(num_set)
    now_set += num_set
  else
    if set == now_set
      ok_set << prime - 1 - start
    end
    start = prime + 1
    now_set.clear
  end
end
if set == now_set
  ok_set << prime_max - start
end
if ok_set.empty?
  puts(-1)
else
  puts(ok_set.max)
end