Q = gets.to_i
Q.times do
  n, k = gets.split.map(&:to_i)

  if k == 1
    puts n - 1
  else
    ok = 100
    ng = 0

    while (ok - ng).abs >= 2
      h = (ok + ng) / 2

      if n <= k ** h
        ok = h
      else
        ng = h
      end
    end

    puts ok
  end
end