import java.util.*;
public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int S = sc.nextInt();
		int W = sc.nextInt();
		String ans = "safe";
		if(W >= S){
			ans = "unsafe";
		}
		System.out.println(ans);
	}
} import java.util.*; util.* java public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int S = sc.nextInt();
		int W = sc.nextInt();
		String ans = "safe";
		if(W >= S){
			ans = "unsafe";
		}
		System.out.println(ans);
	}
} Main public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int S = sc.nextInt();
		int W = sc.nextInt();
		String ans = "safe";
		if(W >= S){
			ans = "unsafe";
		}
		System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		int S = sc.nextInt();
		int W = sc.nextInt();
		String ans = "safe";
		if(W >= S){
			ans = "unsafe";
		}
		System.out.println(ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int S = sc.nextInt(); S sc.nextInt() sc.nextInt sc int W = sc.nextInt(); W sc.nextInt() sc.nextInt sc String ans = "safe"; ans "safe" if(W >= S){
			ans = "unsafe";
		} W >= S W S {
			ans = "unsafe";
		} ans = "unsafe" ans "unsafe" System.out.println(ans) System.out.println System.out System System.out ans String args[] args public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int S = sc.nextInt();
		int W = sc.nextInt();
		String ans = "safe";
		if(W >= S){
			ans = "unsafe";
		}
		System.out.println(ans);
	}
} public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int S = sc.nextInt();
		int W = sc.nextInt();
		String ans = "safe";
		if(W >= S){
			ans = "unsafe";
		}
		System.out.println(ans);
	}
} Main
import java.util.*;
public class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int S = sc.nextInt();
		int W = sc.nextInt();
		String ans = "safe";
		if(W >= S){
			ans = "unsafe";
		}
		System.out.println(ans);
	}
}