#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define int long long
#define mp make_pair
#define endl "\n"
#define pii pair<int,int> 
#define ff first
#define ss second
#define mii map<int,int>
#define si set<int>
#define sti stack<int>
#define qi queue<int>
#define vi vector<int>
#define pq priority_queue<int>
#define IOS ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
const int M=1e9+7;

int32_t main(){
    IOS;
    int s,w;
    cin>>s>>w;
    if(w>=s) cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;
}
