N, M, K = gets.split.map &:to_i
edges = []
M.times.map{
  a, b, c = gets.split.map &:to_i
  edges << [a, b, c] << [b, a, c]
}
tollages = gets.split.map &:to_i
starts = []
checked = [true] * -~N

tollages.each{|tollages|
  nxt = [false] * -~N
  edges.each{|a, b, c|
    nxt[b] = true if checked[a] && c == tollages
  }
  checked = nxt
}

p checked.count(true)
puts (1..N).select{|i|checked[i]}*" "