import java.util.*;
import java.io.*;

public class Main {
		public static void main(String[] args) throws IOException {
		
		// 入出力高速化 java.io.* とthrows IOExceptionを忘れずに
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		String[] SW = br.readLine().split(" ");
		
		int S = Integer.parseInt(SW[0]);
		int W = Integer.parseInt(SW[1]);
		
		System.out.println(S>W? "safe" : "unsafe");
	}
}

/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