#include <bits/stdc++.h>
#define rep(i,cc,n) for(int i=cc;i<=n;++i)
#define drep(i,cc,n) for(int i=cc;i>=n;--i)
#define sz(s) (int)(s.size())
#define vecprint(v) rep(i,0,v.size()-1)cout << v[i] << " ";cout << endl;
#define arrprint(v,n) rep(i,0,n-1)cout << v[i] << " ";cout << endl;
#define matprint(v,n,m) rep(i,0,n-1){rep(j,0,m-1){cout << v[i][j] << " ";}cout << endl;}
#define SORT(v) sort(v.begin(), v.end())
#define REV(v) reverse(v.begin(), v.end())
using namespace std;
const int mod=1000000007;
const int INF=1001001001;
typedef long long ll;
typedef pair<int,int> P;
template<typename T>
using priority_queue_rev = priority_queue<T, vector<T>, greater<T>>; //小さいものから取り出す

int main(){
    int s,w;
    string ans;
    cin >> s >> w;
    if(w >= s)ans = "unsafe";
    else ans = "safe";

    cout << ans << endl;
//  printf("%.10f\n",ans);

    return 0;
}