Problem:
Score : 100 points

Problem Statement

There are S sheep and W wolves.

If the number of wolves is greater than or equal to that of sheep, the wolves will attack the sheep.

If the wolves will attack the sheep, print unsafe; otherwise, print safe.

Constraints

1 \leq S \leq 100

1 \leq W \leq 100

Input

Input is given from Standard Input in the following format:

S W

Output

If the wolves will attack the sheep, print unsafe; otherwise, print safe.

Sample Input 1

4 5

Sample Output 1

unsafe

There are four sheep and five wolves. The number of wolves is not less than that of sheep, so they will attack them.

Sample Input 2

100 2

Sample Output 2

safe

Many a sheep drive away two wolves.

Sample Input 3

10 10

Sample Output 3

unsafe

Solution in Common Lisp (SBCL 2.0.3) (judge verdict: Wrong Answer)

(defun f (n)
  (- (char-code n) 48))

(defun ff (lst)
  (let* ((n (reverse lst)))
    (loop :for k :from 0
          :for j :in n
          :sum (* j (expt 10 k)))))

(let* ((len (map 'list #'f (concatenate 'list (read-line))))
       (ln (1- (length len))))
  (princ (loop :for k :from 0 :upto (- ln 3)
               :sum (loop :for x :from (+ k 3) :upto ln
                          :for y := (subseq len k (1+ x))
                          :count (= 0 (mod (ff y) 2019))))))