/*		author:: ajeet  */
/*			*/

	#include<bits/stdc++.h>
	using namespace std;
	#define int long long int
	#define pb push_back
	const int mod=1e9+7;
	#define all(x) x.begin(),x.end()
	#define endl '\n'
	#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
	int32_t main(){
		IOS;
		int w,s;
		cin>>w>>s;
		if(w>=s) cout<<"unsafe"<<endl;
		else cout<<"safe"<<endl;
		return 0;
	}
