(defn r-squared [x y]
 (+ (* (- 0.5 x) (- 0.5 x))
    (* (- 0.5 y) (- 0.5 y))))

(loop [hits 0]
  (let [x (rand)
        y (rand)]
    (def Rs (r-squared x y)))
 (if (< Rs 0.25) (def hits (+ hits 1)))
 (def pi (* 4 (/ hits throws)) )
 (println pi)
)