#include <stdio.h>
#include <string.h>
#include<stdbool.h>
#include<stdlib.h>

int sheep = 0;

int wolf = 0;

char str[200];

int main(void) {

	fgets(str, sizeof(str), stdin);

	sscanf(str, "%d %d", &sheep, &wolf);

	if (sheep > wolf) {

		printf("%s\n","safe");

	}
	else
	{
		printf("%s\n", "unsafe");
	}



	return false;



}