#include<bits/stdc++.h>
//using namespace std;
#define rep(i,j,n) for(int i=(int)(j);i<(int)(n);i++)
#define REP(i,j,n) for(int i=(int)(j);i<=(int)(n);i++)
#define per(i,j,n) for(int i=(int)(j);(int)(n)<=i;i--)
#define ll long long
#define ALL(a) (a).begin(),(a).end()
#define disup(A,key) distance(A.begin(),upper_bound(ALL(A),(ll)(key)))
#define dislow(A,key) distance(A.begin(),lower_bound(ALL(A),(ll)(key)))
#define pb push_back
#define mp make_pair
#define endl "\n"
using std::cin;
using std::cout;
using std::vector;
using std::pair;
using std::string;
using std::upper_bound;
using std::lower_bound;
using vi=vector<ll>;
using vii=vector<vi>;
using pii=pair<ll,ll>;
const ll MOD=1e9+7;
const int MAX=1e5;
const ll INF=(1ll<<62)-1;
signed main(){
    int S,W; cin>>S>>W;
    string ans="safe";
    if(W>=S) ans="unsafe";
    cout<<ans<<endl;
}