#include<bits/stdc++.h>
 using namespace std;
 
typedef long long int ll;
#define endl "\n"
#define fi first
#define sec second 
#define pb push_back
#define test cout<<"debuged\n";
#define INF ll(1e18)
#define MOD 1000000007
#define debug(x) cout<<x<<"\n";
#define pll pair<ll,ll>
#define mp make_pair
#define Minato_Namikaze ios_base::sync_with_stdio(false) , cin.tie(NULL);
#define all(v) v.begin(),v.end()
#define MAX 200015
 
int main()
{
 
 
ll w,s;
cin>>w>>s;
if(w<=s)cout<<"unsafe\n";
else cout<<"safe\n";

}