import java.util.*;
import java.io.*;

class Main {
	public static void main (String[] args) {
		Scanner input=new Scanner(System.in);
		int s,w;
		s=input.nextInt();
		w=input.nextInt();
		if(w>=s)
		    System.out.println("unsafe");
		 else
		  System.out.println("safe");
		input.close();
	}
}
/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