(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((a (read))
         (p0 (/ (float (read) 0d0) 100d0))
         (p1 (/ (float (read) 0d0) 100d0))
         (p2 (/ (float (read) 0d0) 100d0))
         (p (make-array 3 :element-type 'double-float :initial-contents (list p0 p1 p2)))
         (dp (make-array (list (+ 81 (- a)) 15 2) :element-type 'double-float :initial-element 0d0)))
    (loop for i from 1 to 14 do (dotimes (j 2) (setf (aref dp 0 i j) (float i 0d0))))
    (loop for i from 1 to (- 80 a) do
          (loop for j from 1 to 14 do
                (dotimes (k 2)
                  (if (= j 1)
                      (setf (aref dp i j k) (* (- 1d0 (aref p k))
                                               (aref dp (1- i) j 0)))
                      (let ((tmp 1d0))
                        (dotimes (l j)
                          (let ((x (if (or (and (zerop l) (zerop k))
                                           (= j (1+ l)))
                                       (aref p 1)
                                       (aref p 2))))
                            (incf (aref dp i j k)
                                  (* tmp x (+ (aref dp (1- i) l 0)
                                              (aref dp i (- j l 1) 1))))
                            (setq tmp (* tmp (- 1d0 x)))))
                        (incf (aref dp i j k)
                              (* tmp (aref dp (1- i) j 0))))))))
    (format t "~f~%" (* 2 (aref dp (- 80 a) 14 0)))))

(main)