import java.util.*;
public class Main{
  public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int H = scan.nextInt();
        int O = scan.nextInt();
        int ans = O-H;
        if(ans>=0){
            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