#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define PI 3.14159265358979323846
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr long long INFL = numeric_limits<long long>::max() / 2;
constexpr int MOD = 1000000007;
using Graph = vector<vector<int>>;



int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int S,W;
    cin >> S >> W;
    if(S<=W) cout << "unsafe" << endl;
    else cout << "safe" << endl;





}
