import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner sc=new Scanner(System.in);
		int S=sc.nextInt();
		int W=sc.nextInt();
		
		if(1<=S&&S<=100) {
			if(1<=W&&W<=100) {
				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