import java.util.Scanner;
public class Main{
 public static void main(String[] args) {
   Scanner kbd = new Scanner(System.in);
  int  n=kbd.nextInt();
  int  w=kbd.nextInt();
  if(n>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