import java.util.*;
public class Main{


	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);

		long s  =sc.nextLong();
		long w  =sc.nextLong();
			if(w>=s) {
				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