        #include <bits/stdc++.h>
        using namespace std;
   #define int long long
   #define PP pair<int,pair<int,int>>
const int MAX = 510000;
const int MOD =  998244353;
const int INV2 = (MOD+1)/2;

     signed main(){
     
       int s,w;
       cin>>s>>w;
       if(s<=w)cout<<"unsafe"<<endl;
       else cout<<"safe"<<endl;
                  
}


        
