include Math

def depth(n,k)
  return n - 1 if k == 1
  # (k^{d+1} - 1)/(k-1) >= n
  # d >= log(n * (k-1) + 1) / log(k) - 1
  (log(n*(k-1) + 1) / log(k) - 1).ceil
end

Q = gets.to_i
puts Q.times.map{ gets.split.map(&:to_i) }
       .map{|n,k| depth(n, k) }