import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int S, W;
        Scanner sc = new Scanner(System.in);
        S = sc.nextInt();
        W = sc.nextInt();
        int check = S > W ? 1 : 0;
        switch (check)
        {
            case 1:
                System.out.println("safe");
                break;
            case 0:
                System.out.println("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