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-----
4 5

-----Sample Output-----
unsafe

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

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