import java.util.Scanner;
public class Main {
	public static void main(String[] args) {

	//変数の読み込み
		Scanner sc = new Scanner(System.in);
		int S = sc.nextInt();
		int W = sc.nextInt();

	//SがWよりも多い場合と、SがW以下の場合で分ける
		if(S > W) {
			System.out.print("safe");
		}
		else {
			System.out.print("unsafe");
		}
	}

}
/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