import java.util.*;

public class Main{
 	
  public static void main(String... args){
  		Scanner scanner = new Scanner(System.in);
 		int s = scanner.nextInt();
    	int w = scanner.nextInt();
    	
    	System.out.println(w>=s? "unsafe":"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