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

public class Main {
  public static void main(final String[] args) throws Exception {
    try (BufferedReader r = new BufferedReader(new InputStreamReader(System.in))) {
      String s = r.readLine();
      String[] a = s.split(" ");
      int sheeps = Integer.parseInt(a[0]);
      int wolves = Integer.parseInt(a[1]);
      if (wolves >= sheeps) {
        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