#include <bits/stdc++.h>
#define int long long
#define float long double
#define PB push_back
#define MP make_pair
#define ss second
#define ff first
#define PI 3.14159265
#define fastrack ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
using namespace std;
const int M = 2007, mod = 998244353;

signed main(){
    fastrack;
    int tt = 1;
    //cin >> tt;
    while(tt--){
        int w, s;
        cin >> w >> s;
        if(w >= s)
            cout << "unsafe" << "\n";
        else
            cout << "safe" << "\n";
    }
    return 0;
}
