(defn make-vec
  [n]
  (->>
    (clojure.string/split (str n) #" ")
    (map #(Integer/parseInt %))))

(defn abc-125a
  []
  (let [v (make-vec (read-line))
        a (nth v 0)
        b (nth v 1)
        t (+ 0.5 (nth v 2))]
    (loop [cnt 0
           idx 1]
      (if (< t (* idx a))
        cnt
        (recur
          (+ cnt b)
          (inc idx))))))

(prn (abc-125a))