#include<bits/stdc++.h>
using namespace std ; 
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define fast ios_base:: sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define int long long int
#define endl "\n"
#define pb push_back
#define bs binary_search
#define lb lower_bound
#define ub upper_bound
#define f first
#define s second
#define pii pair<int,int> 
template<class T> inline istream& operator>>(istream& str, vector<T> &a) { for (auto &i : a) str >> i; return str; }

long long M  = 1e9+7;
 
signed main(){
    fast;
    int s,w; cin >> s >> w;
    if(w > s){
    	cout << "unsafe" << endl;
    }
    else
    	cout << "safe" << endl;
}
