require "prime"

def f(a)
  max = -1
  start = 1
  last = Prime.each(PRIME_MAX).inject([]){|curr, pr|
    pr_a = pr.to_s.chars

    if !((curr | pr_a) - a).empty?
      max = [max, pr - start - 1].max if curr.size == a.size
      start = pr + 1
      []
    else
      curr | pr_a
    end
  }
  max = [max, PRIME_MAX - start].max if last.size == a.size
  max
end

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

p N == 10 ? PRIME_MAX-1 : f(A)