(define (pocket-money x a b)
  (let ([n (quotient x a)])
    (+ (* n (- b 1)) x)))

(define (over-c? a b c)
  (lambda (x) (>= (pocket-money x a b) c)))

(define (bsearch f l r)
  (cond [(= 1 (- r l)) r]
        [else (let ([m (quotient (+ l r) 2)])
                (if (f m) (bsearch f l m) (bsearch f m r)))]))

(define (main args)
  (let* ([a (read)]
         [b (read)]
         [c (read)])
    (print (bsearch (over-c? a b c) 0 c)))
  0)