import java.util.*;
public class Main
{
	public static  void main(String args[])
	{
		Scanner sc=new Scanner(System.in);
		String h[]=sc.nextLine().split(" ");
		System.out.println(Integer.parseInt(h[0])>Integer.parseInt(h[1])?"safe":"unsafe");
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz