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

public class Main{
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] array = in.readLine().split(" ");
    int S = Integer.parseInt(array[0]);
    int W = Integer.parseInt(array[1]);
    System.out.println(S>W?"safe":"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