import java.util.*; 
import java.lang.*; 

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		
		int S = scan.nextInt();
                int W = scan.nextInt();
                
                if(S<=W){
                    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