# frozen_string_literal: true
in_n, in_m = gets.chomp.split.map(&:to_i)
in_uv = in_m.times.map { gets.chomp.split.map(&:to_i) }
in_k = gets.chomp.to_i
in_a =
  if in_k > 0
    gets.chomp.split.map(&:to_i).to_set
  else
    Set[]
  end

edges = Hash.new { |h, k| h[k] = Set.new }

in_uv.each do |u, v|
  5.times do |i|
    shift = in_n * i
    if in_a.include?(v)
      edges[u + shift] << v + shift + in_n if i < 4
    else
      edges[u + shift] << v
    end

    if in_a.include?(u)
      edges[v + shift] << u + shift + in_n if i < 4
    else
      edges[v + shift] << u
    end
  end
end

queue = [1]
distances = {}
distances[1] = 0
until queue.empty?
  q = queue.shift
  edges[q].each do |e|
    if distances[e].nil?
      distances[e] = distances[q] + 1
      queue << e
    end
  end
end

puts (5.times.map { |i| distances[in_n + in_n * i] }.compact.min || -1)