import java.io.*;
import java.util.*;
public class Main
{
  public static void main(String args[])throws IOException
  {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer(br.readLine());
    int s = Integer.parseInt(st.nextToken());
    int w = Integer.parseInt(st.nextToken());
    if(s>w)
    	System.out.println("safe");
    else
    	System.out.println("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