#include <iostream>
#include <queue>
#include <algorithm>
#include <set>
#include <vector>
#include <string>

using namespace std; using ll=long long; const int INF=1e9; using P=pair<ll,ll>;

int main() {
  int s,q; cin>>s>>q;
  if (s<=q) cout<<"unsafe"<<endl;
  else cout<<"safe"<<endl;
}