import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
	private static void solveTC(int __) {
		
		/* For Google */
//		ans.append("Case #").append(__).append(": ");

//		code start

		int s=scn.nextInt(),w=scn.nextInt();
		if (w>=s){
			print("unsafe");
		}else {
			print("safe");
		}

//		code end

		ans.append("\n");
	}

	static void print(Object obj) {
		ans.append(obj.toString());
	}

	public static void main(String[] args) {
		
		scn = new Scanner();
//		int t = scn.nextInt();
		int t = 1;
		for (int i = 1; i <= t; i++) {
			ans = new StringBuilder();
			solveTC(i);
			System.out.print(ans);
		}
		
	}
	
	static Scanner scn;
	static StringBuilder ans;
	
	//Fast Scanner
	static class Scanner {
		BufferedReader br;
		StringTokenizer st;
		
		public Scanner() {
			br = new BufferedReader(new
					InputStreamReader(System.in));
		}
		
		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}
		
		int nextInt() {
			return Integer.parseInt(next());
		}
		
		long nextLong() {
			return Long.parseLong(next());
		}
		
		double nextDouble() {
			return Double.parseDouble(next());
		}
		
		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
		
		int[] nextIntArray(int n) {
			int[] array = new int[n];
			for (int i = 0; i < n; i++) {
				array[i] = nextInt();
			}
			return array;
		}
		
		Integer[] nextIntegerArray(int n) {
			Integer[] array = new Integer[n];
			for (int i = 0; i < n; i++) {
				array[i] = nextInt();
			}
			return array;
		}
		
		long[] nextLongArray(int n) {
			long[] array = new long[n];
			for (int i = 0; i < n; i++) {
				array[i] = nextLong();
			}
			return array;
		}
		
		String[] nextStringArray() {
			return nextLine().split(" ");
		}
		
		String[] nextStringArray(int n) {
			String[] array = new String[n];
			for (int i = 0; i < n; i++) {
				array[i] = next();
			}
			return array;
		}
	}
}
/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