#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#define FPEN freopen("in.txt", "r", stdin);
#define debug(...)                                                             \
    { cerr << "# " << __VA_ARGS__ << "\n"; }
#else
#define debug(...)
#define FPEN
#endif
const int maxn = 200009;
typedef long long i64;
typedef pair<i64, i64> pi64;
typedef pair<int, int> pi;
const i64 MOD = 119 << 23 | 1;
class {
  public:
    void solve() {
        int s, w;
        cin >> s >> w;
        if (w >= s) {
            cout << "unsafe";
        } else {
            cout << "safe";
        }
    }
} NSPACE;
int main() {
    FPEN;
    ios_base::sync_with_stdio(false);
    cout.tie(0);
    cin.tie(0);
    NSPACE.solve();
}