(define (read-list q)
  (cond [(zero? q) '()]
        [else (let* ([n (read)]
                     [k (read)])
                (cons (list n k) (read-list (- q 1))))]))

(define (solve nk)
  (let ([n (car nk)]
        [k (cadr nk)])
    (cond [(= k 1) (- n 1)]
          [else (- (inexact->exact (ceiling (log (+ 1 (* n (- k 1))) k))) 1)])))

(define (main args)
  (let* ([q (read)]
         [lnk (read-list q)])
    (for-each print (map solve lnk)))
  0)