#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimization ("Ofast")
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,n) for(int i=1;i<n;i++)
#define all(v) v.begin(),v.end()
#define P pair<int,int>
#define siz(s) (int)s.size()

template<class T> inline bool chmin(T &a, T b) {
	if(a>b){a=b;return true;}
	return false;
}
template<class T> inline bool chmax(T &a, T b) {
	if(a<b){a=b;return true;}
	return false;
}
template<class T> inline int getidx(vector<T> &v, T a) {
	return lower_bound(all(v), a) - v.begin();
}

constexpr int mod=998244353;
constexpr int inf=3e18;


signed main(){
	cin.tie(0);ios::sync_with_stdio(false);
	int a,b;cin>>a>>b;
	if(b>=a)cout<<"unsafe"<<endl;
	else cout<<"safe"<<endl;
}
