//PLUS ULTRA
//one who atops 

#include<bits/stdc++.h>
using namespace std;
     
     
#define SPEED ios::sync_with_stdio(false); cin.tie(0); cout.tie(0)
#define pb push_back 
#define mp make_pair
#define forn(i,st,n) for(int i = st; i < n ; i++)
#define nfor(i,st,n) for(int i = st; i >= n ; i--)
#define ss second
#define ff first
#define ll long long 

typedef pair <int , int> pii;

const int N = 1e5 + 10 , mod =  1000000007;

void solve(){
    int s , w;

    cin >> s >> w;

    if(w >= s)cout << "unsafe";
    else cout << "safe";



}

int main(){
    SPEED;

   solve();


    #ifdef LOCAL

    

    return 0;
}
      
       
