import javax.swing.text.html.HTMLDocument;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.nio.Buffer;
import java.util.*;

class Main {
    public static void main(String[] args){
        try {
            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
            String[] ss=br.readLine().split(" ");
            int s=Integer.parseInt(ss[0]);
            int w=Integer.parseInt(ss[1]);
            if(w>=s){
                System.out.println("unsafe");
            }else{
                System.out.println("safe");
            }
        } catch (Exception e) {
            System.out.println("kkkk "+ e.getMessage());
        }
    }
    static void shuffle(int[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }
}
/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