#include <bits/stdc++.h>
#define WHOLE(v) (v).begin(), (v).end()
#define REV_WHOLE(v) (v).rbegin(), (v).rend()
using i64 = int64_t;
using namespace std;
template<class F>auto recursive(F f){return[f](auto...a){return f(f,a...);};}
template<class I,class V=typename I::value_type>V sum_up(const I&l,const I&r){V v;for(I i=l;i!=r;i++)v=i==l?*i:v+*i;return v;}
template<class I,class T=iterator_traits<I>>I operator+(I it,int n){for(int i=0;i<n;i++)it++;return it;}
template<class I,class T=iterator_traits<I>>I operator-(I it,int n){for(int i=0;i<n;i++)it--;return it;}
template<class T>using rev_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<class T>using vector2d=vector<vector<T>>;
struct fixprec{int p;fixprec(int p):p(p){}};
ostream&operator<<(ostream&o,fixprec f){return o<<fixed<<setprecision(f.p);}
void R_YESNO(bool p){cout<<(p?"YES":"NO")<<endl;}
void R_YesNo(bool p){cout<<(p?"Yes":"No")<<endl;}
int main() {
    int S, W;
    cin >> S >> W;
    if(W >= S) cout << "unsafe" << endl;
    else cout << "safe" << endl;
    return 0;
}

