import java.util.Scanner;

public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int s = sc.nextInt();
		int w = sc.nextInt();

		sc.close();
		String ans = "safe";
		if (w >= s ) {
			ans = "unsafe";
		}

		System.out.println(ans);
	}
} import java.util.Scanner; Scanner 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();

		sc.close();
		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();

		sc.close();
		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();

		sc.close();
		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 sc.close() sc.close 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();

		sc.close();
		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();

		sc.close();
		String ans = "safe";
		if (w >= s ) {
			ans = "unsafe";
		}

		System.out.println(ans);
	}
} Main
import java.util.Scanner;

public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int s = sc.nextInt();
		int w = sc.nextInt();

		sc.close();
		String ans = "safe";
		if (w >= s ) {
			ans = "unsafe";
		}

		System.out.println(ans);
	}
}
