import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

				Scanner sc = new Scanner(System.in);

				int sheep = sc.nextInt();
				int wolf = sc.nextInt();

				if(wolf >= sheep) {
					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