import java .util.Scanner;
 
public class Main{
    public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int s = Integer.parseInt(sc.next());
    	int w = Integer.parseInt(sc.next());
    
 		if(w >= s){
     	 	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