import java.util.Scanner;

public class Main{
  public static void main(String args[]){
    
    Scanner scan;
    int sheep;
    int wolves;
    
    sheep = 0;
    wolves = 0;
    
    scan = new Scanner(System.in);
    sheep = scan.nextInt();
    wolves = scan.nextInt();
    
    if (sheep > wolves){
      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