import java.util.Scanner;


public class Main{
    
      public static int w,s;
      
      public static String isSafe(){
            if(w >= s) return "unsafe";
            return "safe";
      }

       public static void main(String []args){
         Scanner x = new Scanner(System.in);
         s = x.nextInt();
         w = x.nextInt();
         String ans = isSafe();
         System.out.println(ans);
        
      }
}
/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