class Node
  attr_reader :id, :siblings
  attr_accessor :state, :parent

  def initialize(id)
    @id = id
    @siblings = []
    @distances = {}
    @state = :white
    @parent = nil
  end

  def add(sibling, distance)
    @siblings << sibling
    @distances[sibling.id] = distance
  end

  def distance_from(other)
    @distances[other.id]
  end
end

if $PROGRAM_NAME == __FILE__
  n = gets.to_i

  nodes = []

  n.times do |id|
    nodes[id] ||= Node.new(id)
    node = nodes[id]

    distances = gets.chomp.split.map(&:to_i)

    distances.each_with_index do |distance, sibling_id|
      next if distance == -1

      nodes[sibling_id] ||= Node.new(sibling_id)
      sibling = nodes[sibling_id]

      node.add(sibling, distance)
    end
  end

  distances = Array.new(n, Float::INFINITY)

  distances[0] = 0

  loop do
    current = nil
    min = Float::INFINITY

    nodes.each do |node|
      next if node.state == :black

      distance = distances[node.id]

      if distance < min
        min = distance
        current = node
      end
    end

    break unless current

    current.state = :black

    current.siblings.each do |sibling|
      next if sibling.state == :black

      distance_from_current = sibling.distance_from(current)

      if distance_from_current < distances[sibling.id]
        distances[sibling.id] = distance_from_current
        sibling.parent = current
        sibling.state = :gray
      end
    end
  end

  sum = 0

  nodes.each do |node|
    next unless node.parent
    sum += node.distance_from(node.parent)
  end

  puts sum
end