Scanf.scanf "%d" (fun q ->
    let calc n k =
        let rec loop i c acc =
            let acc = acc + c in
            if n <= acc then i else loop (i + 1) (c * k) (acc)
        in
        loop 0 1 0
    in
    for i = 1 to q do
        Scanf.scanf " %d %d" (fun n k ->
            Printf.printf "%d\n" @@
                if k = 1 then n - 1 else calc n k
        )
    done
)