import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int s = sc.nextInt();
		int w = sc.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