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.

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.

Constraints

• $1 \leq S \leq 100$
• $1 \leq W \leq 100$

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

见题面 Input 部分

见题面 Output 部分