import java.io.*;
import java.lang.reflect.Array;
import java.util.*;

public class Main {

    public static void main(String[] args) {

        //r(a, 0, "");
        Scanner in = new Scanner(System.in);
            int N = in.nextInt();
            int W = in.nextInt();
            if(W >= N) {
                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