import java.util.*;

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


        int s = sc.nextInt();
        int w = sc.nextInt();


        if(s > w){
            System.out.println("safe");
        }else{
            System.out.println("unsafe");
        }


    }
}