local q = io.read("*n")
for i = 1, q do
  local n, k = io.read("*n", "*n")
  if k == 1 then
    print(n - 1)
  else
    local d = 0
    local c = 1
    local mul = 1
    while c < n do
      mul = mul * k
      c = c + mul
      d = d + 1
    end
    print(d)
  end
end