gets.to_i.times do
  a, b, c = gets.split.map(&:to_i)
  if c == 1
    puts -1
    next
  end
  dfs = Hash.new do |h, n|
    if n == 0
      h[n] = 0
    elsif n % c == 0
      h[n] = [h[n / c] + b, (n + c - 2) / (c - 1) * b].min
    else
      h[n] = [h[n - n % c] + b, (n + c - 2) / (c - 1) * b].min
    end
  end
  puts dfs[a]
end