#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define lvector vector<ll> 
#define P pair<ll,ll>
#define ALL(a) (a).begin(),(a).end()
#define YESNO(i) if((i)) puts("YES");else puts("NO");
#define YesNo(i) if((i)) puts("Yes");else puts("No");
#define yesno(i) if((i)) puts("yes");else puts("no");
#define rep(i,n) for(ll (i)=0; (i)<(n); ++(i))
#define print(a) cout << (a) << endl

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  ll s,w;cin>>s>>w;
  if(s<=w) puts("unsafe");else puts("safe");
  return 0;
}