require "prime"

def a2m(a)
  a.inject(0){|r, n| r | 1<<n}
end

def f(a)
  mask = a2m(a)

  max = -1
  start = 1
  curr_mask = 0
  primes = Prime.each(PRIME_MAX).map{|pr|
    [pr, a2m(pr.to_s.chars.map(&:to_i))]
  }
  primes.size.times{|i|
    pr, pr_mask = primes[i]

    curr_mask |= pr_mask
    if (curr_mask & ~mask) != 0
      start = pr + 1
      curr_mask = 0
    elsif curr_mask == mask
      last = i == primes.size-1 ? PRIME_MAX : primes[i+1][0]
      max = [max, last - start - 1].max
    end
  }
  max
end

PRIME_MAX = 5_000_000
N = gets.to_i
A = gets.split.take(N).map(&:to_i)

puts PRIME_MAX-1 if N == 10
p f(A)