#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream>
#include <random>
#include<map>
#include <iomanip>
#include <time.h>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <cassert>
#include<fstream>
#include <unordered_map>
#include <cstdlib>
#include <complex>
using namespace std;
#define arep(i,x,n) for(int i=int(x);i<(int)(n);i++)
#define rep(i,n) for(long long i = 0;i < n;++i)
#define pi 3.141592653589793
#define eps 0.00000001
#define INF 1e9+7  
using ll = long long; 
using P=pair<int,int>;
using lP=pair<ll,ll>;
using fP=pair<double,double>;


int main(){
    int s,w;
    cin>>s>>w;
    if(w>=s)cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;
    
    return 0;
}