#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define debug(a) cout << #a << ": " << a << endl
#define sz(a) int(a.size())
#define rep(i,n) for(int i=0;i<n;i++)
#define forr(i, st, en) for(int i = st; i <= en; i++)
#define all(v) (v).begin(),(v).end()

#define fast cin.tie(0); ios::sync_with_stdio(false)

int32_t main(){ fast;
	int s, w; cin>>s>>w;
	if(w >= s){
		cout<<"unsafe"<<endl;
	}
	else cout<<"safe"<<endl;
}
