#include <iostream>
#include <algorithm>
#define flush fflush(stdout)
using namespace std;
typedef long long ll;
typedef pair<ll, int> P;
const int mod = (int)1e9 + 7, INF = (int)1e9;
const int di[4] = { 1,0,-1,0 }, dj[4] = { 0,1,0,-1 };


int main(void) {
	int s, w;


	scanf("%d%d", &s, &w);

	if (s <= w) {
		printf("un");
	}

	printf("safe\n");

	return 0;
}