#include <bits/stdc++.h>
using namespace std;

#define mp make_pair
#define fi first
#define se second
#define forn(i, a, b) for(int i = (a); i < (b); i++)
#define rep(i, n) forn(i, 0, (n))
#define all(x) x.begin(), x.end()
#define len(x) (int)x.size()
#define endl '\n'

#define ld long double
#define vc vector
#define pq priority_queue
#define uset unordered_set
#define umap unordered_map
#define vi vc<int>
#define pii pair<int, int>
#define vii vc<pii>

inline void FASTIO(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
}

void solve(){
    return;
}

signed main(){
    FASTIO();
    int n, k; cin >> n >> k;
    if(k >= n) cout << "unsafe";
    else cout << "safe";
}
