import java.util.*;
class Main{
public static void main(String[] args) {
  Scanner reader =new Scanner (System.in);
  int i=reader.nextInt();
  int d=reader.nextInt();
  if(i<=d)
  {
    System.out.println("unsafe");
  }else
    System.out.println("safe");
}
}

/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