import java.util.*;
class Main{
  public static void main(String[]args){
    Scanner s=new Scanner(System.in);
    int n=s.nextInt();
    int a=s.nextInt();
    if(n<=a){
    	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