import java.util.Scanner;

public class Main{
 public static void main(String[] args){
  Scanner sc = new Scanner(System.in);
  int sheep = sc.nextInt(), wolf=sc.nextInt();
  if(wolf>=sheep) System.out.println("unsafe");
  else System.out.println("safe");
 }
}
		
/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