import java.util.*;

public class Main {
    
    public static List<Integer> P;
    public static void main(String args[]){
        Scanner scanner = new Scanner(System.in);
        final int S = scanner.nextInt();
        final int W = scanner.nextInt();
        if(S <= W){
            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