//Patwari26
#include<bits/stdc++.h>
using namespace std;

#define ll          long long
#define pb          push_back
#define endl        '\n'
#define mii         map<ll,ll>
#define pii         pair<ll,ll>
#define vi          vector<ll>
#define all(a)      (a).begin(),(a).end()
#define F           first
#define S           second
#define sz(x)       (ll)x.size()
#define hell        1000000007
#define INF         (1ll<<60)
#define rep(i,a,b)  for(ll i=a;i<=b;i++)
#define rrep(i,a,b)  for(ll i=a;i>=b;i--)
#define ios ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define time        cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
ll gcd(ll a, ll b) { return b == 0 ? a : gcd(b, a % b); }
ll lcm(ll a, ll b) { return a * (b / gcd(a, b)); }
const int N=100005;
void solve(){
    ll s,w;
    cin>>s>>w;
    if(w>=s){
        cout<<"unsafe"<<endl;
    }
    else cout<<"safe"<<endl;
}
signed main()
{
    ios
    int TESTS=1;
    //cin>>TESTS;
    while(TESTS--){
        solve();
    }
    time
    return 0;
}