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 Fortran (GNU Fortran 9.2.1) (judge verdict: Runtime Error)

program sample
implicit none
integer A,B,C,D
READ(*,*)A,B,C,D
10 CONTINUE
DO WHILE (C>0.OR.A>0)
C=C-B
If (C<=0) then
   WRITE(*,*) "Yes"
END IF
A=A-D
IF(A<=0.AND.C>0) then
   WRITE(*,*) "No"
END IF
END DO
stop
end program sample