import java.util.Scanner;

public class Main {
        public static void main(String[] args) {
                Scanner scan = new Scanner(System.in);

                int sheep = scan.nextInt();
                int wolf = scan.nextInt();

                if (sheep <= wolf) {
                	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