#include <bits/stdc++.h>
 
using namespace std;

typedef long long ll;
// #define int ll
#define pb push_back
const int INF = 1e9;

signed main(){

	ios_base::sync_with_stdio(false);
	cin.tie(0);




	int s,w;
	cin>>s>>w;
	if (w>=s)
		cout<<"unsafe";
	else
		cout<<"safe";
	

	return 0;
}