#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<ll,ll>;
using Map = map<string,ll>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
ll INF=1LL<<60;
ll MOD=1000000007;

int main(){
    ll S;
    cin >> S;
    ll W;
    cin >> W;
    if(W>=S)cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;

    return 0;
}
