#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
  
using namespace std;
using namespace __gnu_pbds;
 
#define ll long long
#define uint unsigned int
#define ull  unsigned long long
#define pb push_back
#define mk make_pair
#define ins insert
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define X first
#define Y second
#define umap unordered_map
#define speed() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define setvalue(d,s,e,n) for(int qwe = s; qwe < e; ++qwe) d[qwe] = n
#define mset multiset
#define pqueue priority_queue
   
template<class T> using oset=tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
        
const int  N = 2e5 + 314;
const int INF = 1e9;
const double PI = acos(-1);
const int MOD = 1e9 + 7;
const double eps = 1e-9;

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

 
int main(){
    speed();
    int t = 1;
    // cin >> t;
    while(t--)solve();
}