import java.util.*;
import java.io.*;
public class Main
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        // int T;
        // T=in.nextInt();
        // while((T--)>0)
        // {
        //     //code comes here
        //     int S,W;
        //     S=in

        // }   

        int S,W;
        S=in.nextInt();
        W=in.nextInt();
        if(W>=S)
        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