import java.util.Scanner;
import java.util.Arrays;

public class Main{
public static void main(String[] args){
Scanner scan=new Scanner(System.in);
int n=scan.nextInt();
int m=scan.nextInt();

if(n<=m){
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