
import java.util.Map.Entry;
import java.util.*;

import org.w3c.dom.css.Counter;

public class Main {
//public class App {

    public static void main(String[] args){
     //スキャン
     Scanner s = new Scanner(System.in);
       // 入力
       int n = Integer.parseInt(s.next());
       int n2 =Integer.parseInt(s.next());
        if(n <= n2){
            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