
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int S = in.nextInt();
        int W = in.nextInt();
        if(S > W){
            System.out.print("safe");
        }
        else{
            System.out.print("unsafe");
        }
        

    }

}