#include <bits/stdc++.h>
using namespace std;
// typedef __uint128_t u128;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef pair<ll, ll> ii;
typedef vector<pair<ll, ll>> vii;
typedef vector<vector<pair<ll, ll>>> vvii;
typedef long double ld;
typedef vector<long double> vld;
typedef vector<vector<long double>> vvld;
typedef vector<bool> vbl;
typedef vector<vector<bool>> vvbl;
#define ff first
#define ss second
#define pb push_back
#define all(c) (c).begin(), (c).end()
const long long MOD = 1e9 + 7;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int s, w;
    cin >> s >> w;
    if (s <= w)
        cout << "unsafe\n";
    else
    {
        cout << "safe\n";
    }
    return 0;
}