#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define vi vector<int>
#define vll vector<ll>
#define pll pair<ll,ll>
#define pii pair<int,int>
#define pb  push_back
#define ppb pop_back
#define mp  make_pair
int main(){
	// #ifndef ONLINE_JUDGE
	// freopen("input.txt", "r", stdin);
	// freopen("output.txt", "w", stdout);
	// #endif
	ios_base::sync_with_stdio(false); 
	cin.tie(NULL);
	ll S,W;
	cin>>S>>W;
	if(S>W) cout<<"safe\n";
	else cout<<"unsafe\n";
}