import java.util.*;
import java.io.*;
public class Main{
  public static void main(String [] args){

	Scanner sc=new Scanner(System.in);
	int a=sc.nextInt();
	int b=sc.nextInt();
	if(a>b){
		System.out.println("safe");
	}
	else{
		System.out.println("unsafe");
	}

  }

}
/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