#include <bits/stdc++.h>
#define ll long long
#define li long int
#define ld long double
#define pl pair<long long, long long>
#define pi pair<int, int>
#define ppl pair<pl, ll>
#define ppi pair<int, pi>
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define LLFOR(i,a,b) for(ll i=a;i<b;i++)
#define fi first
#define se second
#define MOD 1000000007
#define M2 998244353
//std::cout <<setprecision(30) << av << endl;
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
   int s, w;
   cin >> s >> w;
   if(s<=w){
    cout << "unsafe" << endl;

   }else{
    cout << "safe" << endl;
   }
}

