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

#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rep1(i, n) for (ll i = 1; i <= (ll)(n); i++)
#define INF 1000000000000
#define MOD 1000000007
using ll = long long;

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