import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        double s = scan.nextDouble();
    	double w = scan.nextDouble();
 
    	if(s <= w){
    		System.out.println("unsafe");
    	} else {
    		System.out.println("safe");
    	}
    	
        scan.close();
    }
}
/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